CVE-2026-43080

CVEs › CVE-2026-43080

Description

In the Linux kernel, the following vulnerability has been resolved: l2tp: Drop large packets with UDP encap syzbot reported a WARN on my patch series [1]. The actual issue is an overflow of 16-bit UDP length field, and it exists in the upstream code. My series added a debug WARN with an overflow check that exposed the issue, that's why syzbot tripped on my patches, rather than on upstream code. syzbot's repro: r0 = socket$pppl2tp(0x18, 0x1, 0x1) r1 = socket$inet6_udp(0xa, 0x2, 0x0) connect$inet6(r1, &(0x7f00000000c0)={0xa, 0x0, 0x0, @loopback, 0xfffffffc}, 0x1c) connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x4, 0x0, 0x0, 0x0, {0xa, 0x4e22, 0xffff, @ipv4={'\x00', '\xff\xff', @empty}}}}, 0x32) writev(r0, &(0x7f0000000080)=[{&(0x7f0000000000)="ee", 0x34000}], 0x1) It basically sends an oversized (0x34000 bytes) PPPoL2TP packet with UDP encapsulation, and l2tp_xmit_core doesn't check for overflows when it assigns the UDP length field. The value gets trimmed to 16 bites. Add an overflow check that drops oversized packets and avoids sending packets with trimmed UDP length to the wire. syzbot's stack trace (with my patch applied): len >= 65536u WARNING: ./include/linux/udp.h:38 at udp_set_len_short include/linux/udp.h:38 [inline], CPU#1: syz.0.17/5957 WARNING: ./include/linux/udp.h:38 at l2tp_xmit_core net/l2tp/l2tp_core.c:1293 [inline], CPU#1: syz.0.17/5957 WARNING: ./include/linux/udp.h:38 at l2tp_xmit_skb+0x1204/0x18d0 net/l2tp/l2tp_core.c:1327, CPU#1: syz.0.17/5957 Modules linked in: CPU: 1 UID: 0 PID: 5957 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:udp_set_len_short include/linux/udp.h:38 [inline] RIP: 0010:l2tp_xmit_core net/l2tp/l2tp_core.c:1293 [inline] RIP: 0010:l2tp_xmit_skb+0x1204/0x18d0 net/l2tp/l2tp_core.c:1327 Code: 0f 0b 90 e9 21 f9 ff ff e8 e9 05 ec f6 90 0f 0b 90 e9 8d f9 ff ff e8 db 05 ec f6 90 0f 0b 90 e9 cc f9 ff ff e8 cd 05 ec f6 90 <0f> 0b 90 e9 de fa ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 4f RSP: 0018:ffffc90003d67878 EFLAGS: 00010293 RAX: ffffffff8ad985e3 RBX: ffff8881a6400090 RCX: ffff8881697f0000 RDX: 0000000000000000 RSI: 0000000000034010 RDI: 000000000000ffff RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff520007acf00 R12: ffff8881baf20900 R13: 0000000000034010 R14: ffff8881a640008e R15: ffff8881760f7000 FS: 000055557e81f500(0000) GS:ffff8882a9467000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000033000 CR3: 00000001612f4000 CR4: 00000000000006f0 Call Trace: <TASK> pppol2tp_sendmsg+0x40a/0x5f0 net/l2tp/l2tp_ppp.c:302 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] sock_write_iter+0x503/0x550 net/socket.c:1195 do_iter_readv_writev+0x619/0x8c0 fs/read_write.c:-1 vfs_writev+0x33c/0x990 fs/read_write.c:1059 do_writev+0x154/0x2e0 fs/read_write.c:1105 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f636479c629 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffffd4241c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f6364a15fa0 RCX: 00007f636479c629 RDX: 0000000000000001 RSI: 0000200000000080 RDI: 0000000000000003 RBP: 00007f6364832b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6364a15fac R14: 00007f6364a15fa0 R15: 00007f6364a15fa0 </TASK> [1]: https://lore.kernel.org/all/20260226201600.222044-1-alice.kernel@fastmail.im/

Overview

State: PUBLISHED
Assigner (CNA): Linux
CVSS severity: high
CVSS score: 7.1 / 10
CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Effective score: 7.1 / 10 HIGH source: CNA overview
CWE(s): —
Reserved: 2026-05-01
Published: 2026-05-06 09:40 UTC
Last updated: 2026-05-12 00:17 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/43xxx/CVE-2026-43080.json
Linked Threat: CVE-2026-43080 — CVE-2026-43080

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-05-06 10:16:21 UTC
NVD last modified: 2026-05-06 13:08:07 UTC
EPSS score: 0.0002 (probability of exploitation in next 30 days)
EPSS percentile: 6.96% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

NVD / KEV / EPSS data refreshed 2026-05-25 09:10 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-27571
Assigner: Linux
Published: May 6, 2026, 7:40:16 AM
Updated: May 11, 2026, 10:17:20 PM
EUVD base score: 0.0 / 10
EUVD-reported EPSS: 0.0200
Vendors: Linux
Products: Linux (patch: 6.19.14)

Linux (patch: 6.12.83)

Linux (patch: 6.6.136)

Linux (patch: 6.18.24)

Linux (3557baabf28088f49bdf72a048fd33ab62e205b1 <9ccce02d501335f59a02f26c878c5e095b16302f)

Linux (patch: 0)

Linux (3557baabf28088f49bdf72a048fd33ab62e205b1 <77c1489398c85a844f90205f5e76fd6bc8bb4089)

Linux (3557baabf28088f49bdf72a048fd33ab62e205b1 <ebe560ea5f54134279356703e73b7f867c89db13)

Linux (3557baabf28088f49bdf72a048fd33ab62e205b1 <86534c97abd6365a9a021fd767a2023e63c44469)

Linux (2.6.23)

Linux (3557baabf28088f49bdf72a048fd33ab62e205b1 <f295fe86e22ff0a2ecebf05e30a387e5cf6f6ddc)

Linux (patch: 7.0)

ENISA description: In the Linux kernel, the following vulnerability has been resolved: l2tp: Drop large packets with UDP encap syzbot reported a WARN on my patch series [1]. The actual issue is an overflow of 16-bit UDP length field, and it exists in the upstream code. My series added a debug WARN with an overflow check that exposed the issue, that's why syzbot tripped on my patches, rather than on upstream code. syzbot's repro: r0 = socket$pppl2tp(0x18, 0x1, 0x1) r1 = socket$inet6_udp(0xa, 0x2, 0x0) connect$inet6(r1, &(0x7f00000000c0)={0xa, 0x0, 0x0, @loopback, 0xfffffffc}, 0x1c) connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x4, 0x0, 0x0, 0x0, {0xa, 0x4e22, 0xffff, @ipv4={'\x00', '\xff\xff', @empty}}}}, 0x32) writev(r0, &(0x7f0000000080)=[{&(0x7f0000000000)="ee", 0x34000}], 0x1) It basically sends an oversized (0x34000 bytes) PPPoL2TP packet with UDP encapsulation, and l2tp_xmit_core doesn't check for overflows when it assigns the UDP length field. The value gets trimmed to 16 bites. Add an overflow check that drops oversized packets and avoids sending packets with trimmed UDP length to the wire. syzbot's stack trace (with my patch applied): len >= 65536u WARNING: ./include/linux/udp.h:38 at udp_set_len_short include/linux/udp.h:38 [inline], CPU#1: syz.0.17/5957 WARNING: ./include/linux/udp.h:38 at l2tp_xmit_core net/l2tp/l2tp_core.c:1293 [inline], CPU#1: syz.0.17/5957 WARNING: ./include/linux/udp.h:38 at l2tp_xmit_skb+0x1204/0x18d0 net/l2tp/l2tp_core.c:1327, CPU#1: syz.0.17/5957 Modules linked in: CPU: 1 UID: 0 PID: 5957 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:udp_set_len_short include/linux/udp.h:38 [inline] RIP: 0010:l2tp_xmit_core net/l2tp/l2tp_core.c:1293 [inline] RIP: 0010:l2tp_xmit_skb+0x1204/0x18d0 net/l2tp/l2tp_core.c:1327 Code: 0f 0b 90 e9 21 f9 ff ff e8 e9 05 ec f6 90 0f 0b 90 e9 8d f9 ff ff e8 db 05 ec f6 90 0f 0b 90 e9 cc f9 ff ff e8 cd 05 ec f6 90 <0f> 0b 90 e9 de fa ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 4f RSP: 0018:ffffc90003d67878 EFLAGS: 00010293 RAX: ffffffff8ad985e3 RBX: ffff8881a6400090 RCX: ffff8881697f0000 RDX: 0000000000000000 RSI: 0000000000034010 RDI: 000000000000ffff RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff520007acf00 R12: ffff8881baf20900 R13: 0000000000034010 R14: ffff8881a640008e R15: ffff8881760f7000 FS: 000055557e81f500(0000) GS:ffff8882a9467000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000033000 CR3: 00000001612f4000 CR4: 00000000000006f0 Call Trace: <TASK> pppol2tp_sendmsg+0x40a/0x5f0 net/l2tp/l2tp_ppp.c:302 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] sock_write_iter+0x503/0x550 net/socket.c:1195 do_iter_readv_writev+0x619/0x8c0 fs/read_write.c:-1 vfs_writev+0x33c/0x990 fs/read_write.c:1059 do_writev+0x154/0x2e0 fs/read_write.c:1105 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f636479c629 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffffd4241c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f6364a15fa0 RCX: 00007f636479c629 RDX: 0000000000000001 RSI: 0000200000000080 RDI: 0000000000000003 RBP: 00007f6364832b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6364a15fac R14: 00007f6364a15fa0 R15: 00007f6364a15fa0 </TASK> [1]: https://lore.kernel.org/all/20260226201600.222044-1-alice.kernel@fastmail.im/

EUVD references (5)

Affected products (2)

Vendor	Product	Versions	Platforms
Linux	Linux	`3557baabf28088f49bdf72a048fd33ab62e205b1` (affected), `3557baabf28088f49bdf72a048fd33ab62e205b1` (affected), `3557baabf28088f49bdf72a048fd33ab62e205b1` (affected), `3557baabf28088f49bdf72a048fd33ab62e205b1` (affected), `3557baabf28088f49bdf72a048fd33ab62e205b1` (affected)	—
Linux	Linux	`2.6.23` (affected), `0` (unaffected), `6.6.136` (unaffected), `6.12.83` (unaffected), `6.18.24` (unaffected), `6.19.14` (unaffected), `7.0` (unaffected)	—

Vendor references (5)

References embedded in the original CVE record by the assigning CNA.

MITRE references (5) cveawg.mitre.org

Pulled from MITRE's CVE Services API by the 🛰 Backfill from MITRE button.

Web references (6)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

https://git.kernel.org/stable/c/02d787fd0922c71c0264449fe82d35983613e4e5 tenable:git.kernel.org
https://git.kernel.org/stable/c/a42452db035577e150ffd9adf98c56fef9fb9408 tenable:git.kernel.org
https://git.kernel.org/stable/c/c2994fd24997ed63d713c03313f863645adb4d6c tenable:git.kernel.org
https://nvd.nist.gov/vuln/detail/CVE-2026-43080 tenable:nvd.nist.gov
https://www.cve.org/CVERecord?id=CVE-2026-43080 tenable:www.cve.org
https://www.first.org/epss/ tenable:www.first.org

NVD-tagged references (5)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://git.kernel.org/stable/c/77c1489398c85a844f90205f5e76fd6bc8bb4089 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/86534c97abd6365a9a021fd767a2023e63c44469 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/9ccce02d501335f59a02f26c878c5e095b16302f 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/ebe560ea5f54134279356703e73b7f867c89db13 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/f295fe86e22ff0a2ecebf05e30a387e5cf6f6ddc 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Remediations (20)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

Microsoft and Adobe Patch Tuesday, April 2026 Security Update Review

web:blog.qualys.com

With Qualys Policy Audit's out-of-the-box mitigation or Compensatory Controls, which reduce the risk of a vulnerability being exploited because the remediation ( fix / patch ) cannot be done immediately, these security controls are not recommended by any industry standards, such as CIS and DISA-STIG.

2026-05-23 21:13 UTC
CISA Warns of Exploited Microsoft Defender 0-Day Flaws

web:cyberpress.org

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added two actively exploited Microsoft Defender vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog, issuing an urgent remediation directive for federal agencies with a due date of June 3, 2026 .

2026-05-23 21:13 UTC
Remediate vulnerabilities with Microsoft Defender Vulnerability ...

web:learn.microsoft.com

Remediate security weaknesses discovered through security recommendations, and create exceptions if needed, in Defender Vulnerability Management.

2026-05-23 21:13 UTC
Security Update Guide - Microsoft

web:portal.msrc.microsoft.com

The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

2026-05-23 21:13 UTC
Microsoft Patch Tuesday April 2026 Fixes 167 Bugs

web:thecyberexpress.com

Microsoft Patch Tuesday: Zero-Day Vulnerabilities in Focus A major focus of this Patch Tuesday April 2026 cycle is the remediation of two zero-day vulnerabilities. One of the most concerning issues is an actively exploited spoofing vulnerability in Microsoft SharePoint Server.

2026-05-23 21:13 UTC
Microsoft Patches Two Actively Exploited Defender Zero-Days on Windows

web:windowsreport.com

Microsoft patched two actively exploited Defender zero-days affecting Windows systems and security components.

2026-05-23 21:13 UTC
Microsoft April 2026 Patch Tuesday fixes 167 flaws, 2 zero-days

web:www.bleepingcomputer.com

Today is Microsoft's April 2026 Patch Tuesday with security updates for 167 flaws, including 2 zero-day vulnerabilities.

2026-05-23 21:13 UTC
Microsoft warns of new Defender zero-days exploited in attacks

web:www.bleepingcomputer.com

On Wednesday, Microsoft started rolling out security patches for two Defender vulnerabilities that have been exploited in zero-day attacks.

2026-05-23 21:13 UTC
2 New Microsoft Defender Zero-Days Exploited—Patch Now ... - Forbes

web:www.forbes.com

Microsoft has confirmed an emergency security update as CISA warns that two new Defender zero-days are being exploited by attackers.

2026-05-23 21:13 UTC
Microsoft Issues Massive Windows Patch for 160+ Bugs ... - TechRepublic

web:www.techrepublic.com

Microsoft's April 2026 Patch Tuesday fixes 165 vulnerabilities, including two zero-days, in one of the company's largest monthly security updates.

2026-05-23 21:13 UTC
Mitigate RedSun Zero-Day Without A Patch | Qualys

web:blog.qualys.com

Key Takeaways RedSun is a critical zero-day vulnerability in Microsoft Defender that allows low-privileged users to gain SYSTEM access No patch is currently available, leaving all Defender-enabled Windows systems potentially exposed Qualys VMDR detects affected assets instantly (QID 92382) TruRisk™ Eliminate enables immediate mitigation , removing exploitability without waiting for a fix ...

2026-06-03 07:49 UTC
Microsoft Patch Tuesday May 2026 - 120 Vulnerabilities Fixed, Including ...

web:cybersecuritynews.com

Microsoft's May 2026 Patch Tuesday lands with a heavy enterprise focus, fixing 120 vulnerabilities across Windows, Office, Azure, developer tools, and Microsoft 365 apps, including 29 remote code execution (RCE) flaws rated Critical.

2026-06-03 07:49 UTC
Zero Day (i.e., Critical) Security Patches for vSphere 8.x Perpetual ...

web:knowledge.broadcom.com

The intent of this article is to help customers that are using VMware vSphere 8.x address the most critical security vulnerabilities. Broadcom will provide all perpetual license customers, including those that have expired support contracts, with access to zero-day security patches, which are defined by Broadcom as patches for Critical Severity Security Alerts with a Common Vulnerability ...

2026-06-03 07:49 UTC
Security Update Guide - Microsoft

web:msrc.microsoft.com

The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.

2026-06-03 07:49 UTC
Security Update Guide - Microsoft Security Response Center

web:msrc.microsoft.com

Security Update Guide - Microsoft Security Response Center

2026-06-03 07:49 UTC
NVD - Home

web:nvd.nist.gov

The NVD is the U.S. government repository of standards based vulnerability management data represented using the Security Content Automation Protocol (SCAP). This data enables automation of vulnerability management, security measurement, and compliance. The NVD includes databases of security checklist references, security-related software flaws, product names, and impact metrics. For ...

2026-06-03 07:49 UTC
VMware ESXi 8.0 Update 3d Release Notes

web:techdocs.broadcom.com

Patch Category Security Patch Severity Critical Host Reboot Required Yes Virtual Machine Migration or Shutdown Required Yes Affected Hardware N/A Affected Software N/A Affected VIBs Included VMware_bootbank_esxio-update_8..3-.60.24585383 VMware_bootbank_loadesxio_8..3-.60.24585383 PRs Fixed N/A CVE numbers N/A Due to their dependency on the ...

2026-06-03 07:49 UTC
Riot says "congrats on your $6k paperweights" as new Valorant anti ...

web:www.gamesradar.com

The latest Vanguard patch is apparently ruthless Valorant's brand of cheat prevention, known as Vanguard, has been somewhat contentious since the FPS launched in 2020. Employing kernel-level ...

2026-06-03 07:49 UTC
Oracle Critical Patch Update Advisory - April 2026

web:www.oracle.com

This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.

2026-06-03 07:49 UTC
Oracle Critical Patch Update Advisory - January 2026

web:www.oracle.com

Oracle Critical Patch Update Advisory - January 2026 Description A Critical Patch Update is a collection of patches for multiple security vulnerabilities. These patches address vulnerabilities in Oracle code and in third party components included in Oracle products. These patches are usually cumulative, but each advisory describes only the security patches added since the previous Critical ...

2026-06-03 07:49 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-43080.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/l2tp/l2tp_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9ccce02d501335f59a02f26c878c5e095b16302f",
              "status": "affected",
              "version": "3557baabf28088f49bdf72a048fd33ab62e205b1",
              "versionType": "git"
            },
            {
              "lessThan": "77c1489398c85a844f90205f5e76fd6bc8bb4089",
              "status": "affected",
              "version": "3557baabf28088f49bdf72a048fd33ab62e205b1",
              "versionType": "git"
            },
            {
              "lessThan": "86534c97abd6365a9a021fd767a2023e63c44469",
              "status": "affected",
              "version": "3557baabf28088f49bdf72a048fd33ab62e205b1",
              "versionType": "git"
            },
            {
              "lessThan": "f295fe86e22ff0a2ecebf05e30a387e5cf6f6ddc",
              "status": "affected",
              "version": "3557baabf28088f49bdf72a048fd33ab62e205b1",
              "versionType": "git"
            },
            {
              "lessThan": "ebe560ea5f54134279356703e73b7f867c89db13",
              "status": "affected",
              "version": "3557baabf28088f49bdf72a048fd33ab62e205b1",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/l2tp/l2tp_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.23"
            },
            {
              "lessThan": "2.6.23",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.136",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.83",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.24",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.14",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.136",
                  "versionStartIncluding": "2.6.23",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.83",
                  "versionStartIncluding": "2.6.23",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.24",
                  "versionStartIncluding": "2.6.23",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.14",
                  "versionStartIncluding": "2.6.23",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "2.6.23",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nl2tp: Drop large packets with UDP encap\n\nsyzbot reported a WARN on my patch series [1]. The actual issue is an\noverflow of 16-bit UDP length field, and it exists in the upstream code.\nMy series added a debug WARN with an overflow check that exposed the\nissue, that's why syzbot tripped on my patches, rather than on upstream\ncode.\n\nsyzbot's repro:\n\nr0 = socket$pppl2tp(0x18, 0x1, 0x1)\nr1 = socket$inet6_udp(0xa, 0x2, 0x0)\nconnect$inet6(r1, &(0x7f00000000c0)={0xa, 0x0, 0x0, @loopback, 0xfffffffc}, 0x1c)\nconnect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x4, 0x0, 0x0, 0x0, {0xa, 0x4e22, 0xffff, @ipv4={'\\x00', '\\xff\\xff', @empty}}}}, 0x32)\nwritev(r0, &(0x7f0000000080)=[{&(0x7f0000000000)=\"ee\", 0x34000}], 0x1)\n\nIt basically sends an oversized (0x34000 bytes) PPPoL2TP packet with UDP\nencapsulation, and l2tp_xmit_core doesn't check for overflows when it\nassigns the UDP length field. The value gets trimmed to 16 bites.\n\nAdd an overflow check that drops oversized packets and avoids sending\npackets with trimmed UDP length to the wire.\n\nsyzbot's stack trace (with my patch applied):\n\nlen >= 65536u\nWARNING: ./include/linux/udp.h:38 at udp_set_len_short include/linux/udp.h:38 [inline], CPU#1: syz.0.17/5957\nWARNING: ./include/linux/udp.h:38 at l2tp_xmit_core net/l2tp/l2tp_core.c:1293 [inline], CPU#1: syz.0.17/5957\nWARNING: ./include/linux/udp.h:38 at l2tp_xmit_skb+0x1204/0x18d0 net/l2tp/l2tp_core.c:1327, CPU#1: syz.0.17/5957\nModules linked in:\nCPU: 1 UID: 0 PID: 5957 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014\nRIP: 0010:udp_set_len_short include/linux/udp.h:38 [inline]\nRIP: 0010:l2tp_xmit_core net/l2tp/l2tp_core.c:1293 [inline]\nRIP: 0010:l2tp_xmit_skb+0x1204/0x18d0 net/l2tp/l2tp_core.c:1327\nCode: 0f 0b 90 e9 21 f9 ff ff e8 e9 05 ec f6 90 0f 0b 90 e9 8d f9 ff ff e8 db 05 ec f6 90 0f 0b 90 e9 cc f9 ff ff e8 cd 05 ec f6 90 <0f> 0b 90 e9 de fa ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 4f\nRSP: 0018:ffffc90003d67878 EFLAGS: 00010293\nRAX: ffffffff8ad985e3 RBX: ffff8881a6400090 RCX: ffff8881697f0000\nRDX: 0000000000000000 RSI: 0000000000034010 RDI: 000000000000ffff\nRBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004\nR10: dffffc0000000000 R11: fffff520007acf00 R12: ffff8881baf20900\nR13: 0000000000034010 R14: ffff8881a640008e R15: ffff8881760f7000\nFS:  000055557e81f500(0000) GS:ffff8882a9467000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000200000033000 CR3: 00000001612f4000 CR4: 00000000000006f0\nCall Trace:\n <TASK>\n pppol2tp_sendmsg+0x40a/0x5f0 net/l2tp/l2tp_ppp.c:302\n sock_sendmsg_nosec net/socket.c:727 [inline]\n __sock_sendmsg net/socket.c:742 [inline]\n sock_write_iter+0x503/0x550 net/socket.c:1195\n do_iter_readv_writev+0x619/0x8c0 fs/read_write.c:-1\n vfs_writev+0x33c/0x990 fs/read_write.c:1059\n do_writev+0x154/0x2e0 fs/read_write.c:1105\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7f636479c629\nCode: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48\nRSP: 002b:00007ffffd4241c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014\nRAX: ffffffffffffffda RBX: 00007f6364a15fa0 RCX: 00007f636479c629\nRDX: 0000000000000001 RSI: 0000200000000080 RDI: 0000000000000003\nRBP: 00007f6364832b39 R08: 0000000000000000 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000\nR13: 00007f6364a15fac R14: 00007f6364a15fa0 R15: 00007f6364a15fa0\n </TASK>\n\n[1]: https://lore.kernel.org/all/20260226201600.222044-1-alice.kernel@fastmail.im/"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T22:17:20.208Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/9ccce02d501335f59a02f26c878c5e095b16302f"
        },
        {
          "url": "https://git.kernel.org/stable/c/77c1489398c85a844f90205f5e76fd6bc8bb4089"
        },
        {
          "url": "https://git.kernel.org/stable/c/86534c97abd6365a9a021fd767a2023e63c44469"
        },
        {
          "url": "https://git.kernel.org/stable/c/f295fe86e22ff0a2ecebf05e30a387e5cf6f6ddc"
        },
        {
          "url": "https://git.kernel.org/stable/c/ebe560ea5f54134279356703e73b7f867c89db13"
        }
      ],
      "title": "l2tp: Drop large packets with UDP encap",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43080",
    "datePublished": "2026-05-06T07:40:16.491Z",
    "dateReserved": "2026-05-01T14:12:55.983Z",
    "dateUpdated": "2026-05-11T22:17:20.208Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}