CVE-2026-43501

CVEs › CVE-2026-43501

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the segments share with daddr (CmprI=0, CmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes). pskb_expand_head() was gated on segments_left == 0, so on earlier segments the push consumed unchecked headroom. Once skb_push() leaves fewer than skb->mac_len bytes in front of data, skb_mac_header_rebuild()'s call to: skb_set_mac_header(skb, -skb->mac_len); will store (data - head) - mac_len into the u16 mac_header field, which wraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB past skb->head. A single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two segment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one pass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv. Fix this by expanding the head whenever the remaining room is less than the push size plus mac_len, and request that much extra so the rebuilt MAC header fits afterwards.

Overview

State: PUBLISHED
Assigner (CNA): Linux
CVSS severity: critical
CVSS score: 9.8 / 10
CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Effective score: 9.8 / 10 CRITICAL source: CNA overview
MSRC score: 7.0 / 10 HIGH MS rating: Moderate
CWE(s): —
Reserved: 2026-05-01
Published: 2026-05-21 12:17 UTC
Last updated: 2026-05-21 12:17 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/43xxx/CVE-2026-43501.json
Linked Threat: CVE-2026-43501 — CVE-2026-43501

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: 2026-05-21 13:16:19 UTC
NVD last modified: 2026-05-21 13:16:19 UTC
EPSS score: 0.0002 (probability of exploitation in next 30 days)
EPSS percentile: 7.22% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

NVD / KEV / EPSS data refreshed 2026-05-25 00:27 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-2026-31276
Assigner: Linux
Published: May 21, 2026, 12:17:49 PM
Updated: May 30, 2026, 10:45:21 AM
EUVD base score (CVSS 3.1): 9.8 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EUVD-reported EPSS: 0.0600
Vendors: Linux
Products: Linux (5.7)

Linux (patch: 0)

Linux (8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <c261d07a80576dc8ccf394ef8f074f8c67a06b37)

Linux (patch: 6.12.86)

Linux (patch: 6.18.27)

Linux (patch: 6.6.140)

Linux (8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <4babc2d9fda2df43823b85d08a0180b68f1b0854)

Linux (8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <9e6bf146b55999a095bb14f73a843942456d1adc)

Linux (patch: 7.1-rc2)

Linux (patch: 7.0.4)

Linux (8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <8e8be63465a5e80394c70324603dfea1bfdad48f)

Linux (8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <7398ebefbfd4f8a31d4f665a4213302fa995494b)
Aliases: GHSA-fqx3-r8j8-73qq

ENISA description: In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the segments share with daddr (CmprI=0, CmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes). pskb_expand_head() was gated on segments_left == 0, so on earlier segments the push consumed unchecked headroom. Once skb_push() leaves fewer than skb->mac_len bytes in front of data, skb_mac_header_rebuild()'s call to: skb_set_mac_header(skb, -skb->mac_len); will store (data - head) - mac_len into the u16 mac_header field, which wraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB past skb->head. A single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two segment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one pass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv. Fix this by expanding the head whenever the remaining room is less than the push size plus mac_len, and request that much extra so the rebuilt MAC header fits afterwards.

EUVD references (5)

Microsoft Security Response Center MSRC

Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-08-12 01:09 UTC (source: CVRF).

MS severity: Moderate
MS CVSS base score: 7.0 / 10 (temporal 6.4)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U
Release: 2026-May

Microsoft remediations / KB articles (2)

CBL-Mariner Releases — Vendor Fix / Security Update (fixed build 6.6.141.1-1)
https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade — None Available / CBL-Mariner Releases

Affected products (2)

Vendor	Product	Versions	Platforms
Linux	Linux	`8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3` (affected), `8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3` (affected), `8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3` (affected), `8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3` (affected), `8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3` (affected)	—
Linux	Linux	`5.7` (affected), `0` (unaffected), `6.6.140` (unaffected), `6.12.86` (unaffected), `6.18.27` (unaffected), `7.0.4` (unaffected), `7.1-rc2` (unaffected)	—

Vendor references (5)

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

Web references (13)

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

MSRC update guide: CVE-2026-43501 msrc
None Available msrc
https://git.kernel.org/stable/c/7398ebefbfd4f8a31d4f665a4213302fa995494b tenable:git.kernel.org
https://git.kernel.org/stable/c/8e8be63465a5e80394c70324603dfea1bfdad48f tenable:git.kernel.org
https://git.kernel.org/stable/c/9e6bf146b55999a095bb14f73a843942456d1adc tenable:git.kernel.org
https://git.kernel.org/stable/c/bde199c72d319a4e207f88daabc888317504e2fb tenable:git.kernel.org
https://git.kernel.org/stable/c/be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e tenable:git.kernel.org
https://git.kernel.org/stable/c/c261d07a80576dc8ccf394ef8f074f8c67a06b37 tenable:git.kernel.org
https://nvd.nist.gov/vuln/detail/CVE-2026-43501 tenable:nvd.nist.gov
https://www.cve.org/CVERecord?id=CVE-2026-43501 tenable:www.cve.org
https://git.kernel.org/stable/c/0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402 tenable:git.kernel.org
https://www.first.org/epss/ tenable:www.first.org
https://git.kernel.org/stable/c/4babc2d9fda2df43823b85d08a0180b68f1b0854 tenable:git.kernel.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/4babc2d9fda2df43823b85d08a0180b68f1b0854 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/7398ebefbfd4f8a31d4f665a4213302fa995494b 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/8e8be63465a5e80394c70324603dfea1bfdad48f 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/9e6bf146b55999a095bb14f73a843942456d1adc 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/c261d07a80576dc8ccf394ef8f074f8c67a06b37 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Remediations (18)

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

cve-details - Red Hat Customer Portal

web:access.redhat.com

Learn about our open source products, services, and company. You are here

2026-05-24 12:02 UTC
THREAT ADVISORY RedSun Zero-Day (Windows Defender) April 17, 2026

web:blackswan-cybersecurity.com

Cloud Files API activity originating outside legitimate OneDrive/sync processes. Mitigation Steps: Apply all Windows updates immediately (monitor MSRC for an emergency RedSun-specific patch . None released as of April 17, 2026 ). Supplement Defender with a secondary EDR solution (e.g., Huntress) capable of detecting Defender bypasses.

2026-05-24 12:02 UTC
Security Advisory Bulletin 064 | Ubiquiti Community

web:community.ui.com

Published: May 21, 2026 Updated: May 22, 2026 Version: 1.1 Revision: 1.1 Summary 1 of 5 A malicious actor with access to the network and high privileges could exploit an Improper Input Validation vulnerability found in UniFi OS devices to execute a Command Injection. Affected Products: UniFi OS Server (Version 5.0.6 and earlier) Mitigation : Update your UniFi OS Server to Version 5.0.8 or later ...

2026-05-24 12:02 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 .

2026-05-24 12:02 UTC
Patch Tuesday, May 2026 Edition - Krebs on Security

web:krebsonsecurity.com

Microsoft expects that exploitation is more likely. May's Patch Tuesday is a welcome respite from April, which saw Microsoft fix a near-record 167 security flaws.

2026-05-24 12:02 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.

2026-05-24 12:02 UTC
CVE-2026-43500 and CVE-2026-43284 analysis

web:socprime.com

Explore Detections CVE - 2026 -43500 and CVE - 2026 -43284 Mitigation Practical CVE - 2026 -43500 mitigation starts with reducing available attack paths before a vendor patch is fully available across environments.

2026-05-24 12:02 UTC
"DirtyFrag" (CVE-2026-43500, CVE-2026-43284) Mitigations - Linode

web:www.linode.com

The " DirtyFrag " ( CVE - 2026 -43500, CVE - 2026 -43284) vulnerabilities are the second in a new series of local privilege escalations in the Linux kernel that have recently been published and which exploit the ability for an unprivileged user to write to the page cache. Similar to the " CopyFail " ( CVE - 2026 -31431) vulnerability in nature, these new attack vectors exploit the esp4/esp6 (used ...

2026-05-24 12:02 UTC
Emergency patch issued for Microsoft Office, 365 over hacking threat - MSN

web:www.msn.com

Original story: Microsoft has released an emergency patch for a vulnerability in the company's Office programs that's already being exploited by hackers.

2026-05-24 12:02 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.

2026-05-24 12:02 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 22:32 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 22:32 UTC
Patch Tuesday, April 2026 Edition - Krebs on Security

web:krebsonsecurity.com

For a clickable, per- patch breakdown, check out the SANS Internet Storm Center Patch Tuesday roundup. Running into problems applying any of these updates?

2026-06-03 22:32 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 22:32 UTC
Microsoft May 2026 Patch Tuesday: Many fixes, but no zero-days

web:www.helpnetsecurity.com

Microsoft has marked May 2026 Patch Tuesday by releasing fixes for 120+ CVE -numbered vulnerabilities, none of which are actively exploited.

2026-06-03 22:32 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.

2026-06-03 22:32 UTC
Dirty Frag (CVE-2026-43284,CVE-2026-43500): Linux Kernel ... - Tenable

web:www.tenable.com

Dirty Frag ( CVE - 2026 -43284, CVE - 2026 -43500) is a Linux kernel local privilege escalation exploit chain with a public PoC affecting major Linux distributions.

2026-06-03 22:32 UTC
Patch Tuesday June 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's June 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-06-03 22:32 UTC

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-43501.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/exthdrs.c"
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          "versions": [
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            },
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              "status": "unaffected",
              "version": "6.18.27",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "7.0.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1-rc2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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              ],
              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: rpl: reserve mac_len headroom when recompressed SRH grows\n\nipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps\nthe next segment into ipv6_hdr->daddr, recompresses, then pulls the old\nheader and pushes the new one plus the IPv6 header back.  The\nrecompressed header can be larger than the received one when the swap\nreduces the common-prefix length the segments share with daddr (CmprI=0,\nCmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes).\n\npskb_expand_head() was gated on segments_left == 0, so on earlier\nsegments the push consumed unchecked headroom.  Once skb_push() leaves\nfewer than skb->mac_len bytes in front of data,\nskb_mac_header_rebuild()'s call to:\n\n\tskb_set_mac_header(skb, -skb->mac_len);\n\nwill store (data - head) - mac_len into the u16 mac_header field, which\nwraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB\npast skb->head.\n\nA single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two\nsegment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one\npass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv.\n\nFix this by expanding the head whenever the remaining room is less than\nthe push size plus mac_len, and request that much extra so the rebuilt\nMAC header fits afterwards."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-21T12:17:49.885Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/8e8be63465a5e80394c70324603dfea1bfdad48f"
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        },
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        },
        {
          "url": "https://git.kernel.org/stable/c/7398ebefbfd4f8a31d4f665a4213302fa995494b"
        },
        {
          "url": "https://git.kernel.org/stable/c/9e6bf146b55999a095bb14f73a843942456d1adc"
        }
      ],
      "title": "ipv6: rpl: reserve mac_len headroom when recompressed SRH grows",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43501",
    "datePublished": "2026-05-21T12:17:49.885Z",
    "dateReserved": "2026-05-01T14:12:56.014Z",
    "dateUpdated": "2026-05-21T12:17:49.885Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}