CVE-2026-43490

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate inherited ACE SID length smb_inherit_dacl() walks the parent directory DACL loaded from the security descriptor xattr. It verifies that each ACE contains the fixed SID header before using it, but does not verify that the variable-length SID described by sid.num_subauth is fully contained in the ACE. A malformed inheritable ACE can advertise more subauthorities than are present in the ACE. compare_sids() may then read past the ACE. smb_set_ace() also clamps the copied destination SID, but used the unchecked source SID count to compute the inherited ACE size. That could advance the temporary inherited ACE buffer pointer and nt_size accounting past the allocated buffer. Fix this by validating the parent ACE SID count and SID length before using the SID during inheritance. Compute the inherited ACE size from the copied SID so the size matches the bounded destination SID. Reject the inherited DACL if size accumulation would overflow smb_acl.size or the security descriptor allocation size.

Overview

State: PUBLISHED
Assigner (CNA): Linux
CVSS severity: high
CVSS score: 8.8 / 10
CVSS vector: AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Effective score: 8.8 / 10 HIGH source: CNA overview
MSRC score: 8.8 / 10 HIGH MS rating: Important
CWE(s): —
Reserved: 2026-05-01
Published: 2026-05-15 07:15 UTC
Last updated: 2026-05-15 07:15 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/43xxx/CVE-2026-43490.json
Linked Threat: CVE-2026-43490 — CVE-2026-43490

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: 2026-05-15 06:16:20 UTC
NVD last modified: 2026-05-20 17:16:23 UTC
NVD CVSS v3.1: 8.8 / 10 HIGH source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Exploitability subscore: 2.8 / 10
Impact subscore: 5.9 / 10
EPSS score: 0.0003 (probability of exploitation in next 30 days)
EPSS percentile: 7.48% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

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-2026-30503
Assigner: Linux
Published: May 15, 2026, 5:15:37 AM
Updated: May 23, 2026, 11:25:58 AM
EUVD base score (CVSS 3.1): 8.8 / 10
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EUVD-reported EPSS: 0.0300
Vendors: Linux
Products: Linux (patch: 6.18.30)

Linux (e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <a7fb771314fb3a265d30f8ac245869a367ab065c)

Linux (e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <1aa60fea7f637c071f529ad6784aecca2f2f0c5f)

Linux (e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <47c6e37a77b10e74f70d845ba4ea5d3cafa00336)

Linux (patch: 6.6.141)

Linux (5.15)

Linux (patch: 6.12.88)

Linux (patch: 7.1-rc3)

Linux (e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <c1d95c995d5bcb24b639200a899eda59cb1e6d64)

Linux (e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <996454bc0da84d5a1dedb1a7861823087e01a7ae)

Linux (patch: 7.0.7)

Linux (patch: 0)
Aliases: GHSA-9hm7-v4rj-6wqj

ENISA description: In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate inherited ACE SID length smb_inherit_dacl() walks the parent directory DACL loaded from the security descriptor xattr. It verifies that each ACE contains the fixed SID header before using it, but does not verify that the variable-length SID described by sid.num_subauth is fully contained in the ACE. A malformed inheritable ACE can advertise more subauthorities than are present in the ACE. compare_sids() may then read past the ACE. smb_set_ace() also clamps the copied destination SID, but used the unchecked source SID count to compute the inherited ACE size. That could advance the temporary inherited ACE buffer pointer and nt_size accounting past the allocated buffer. Fix this by validating the parent ACE SID count and SID length before using the SID during inheritance. Compute the inherited ACE size from the copied SID so the size matches the bounded destination SID. Reject the inherited DACL if size accumulation would overflow smb_acl.size or the security descriptor allocation size.

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 2026-07-28 03:00 UTC (source: CVRF).

MS severity: Important
MS CVSS base score: 8.8 / 10 (temporal 8.8)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Release: 2026-May

Affected products (2)

Vendor	Product	Versions	Platforms
Linux	Linux	`e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9` (affected), `e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9` (affected), `e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9` (affected), `e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9` (affected)	—
Linux	Linux	`5.15` (affected), `0` (unaffected), `6.12.88` (unaffected), `6.18.30` (unaffected), `7.0.7` (unaffected), `7.1-rc3` (unaffected)	—

Vendor references (4)

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

MITRE references (4) cveawg.mitre.org

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

Web references (4)

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-2026-43490 msrc
https://www.first.org/epss/ tenable:www.first.org
https://nvd.nist.gov/vuln/detail/CVE-2026-43490 tenable:nvd.nist.gov
https://www.cve.org/CVERecord?id=CVE-2026-43490 tenable:www.cve.org

NVD-tagged references (4)

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/1aa60fea7f637c071f529ad6784aecca2f2f0c5f 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/47c6e37a77b10e74f70d845ba4ea5d3cafa00336 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/996454bc0da84d5a1dedb1a7861823087e01a7ae 416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/c1d95c995d5bcb24b639200a899eda59cb1e6d64 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Remediations (17)

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 20:51 UTC
Oracle Critical Patch Update (CPU) April 2026 for Oracle Java SE

web:docs.oracle.com

Oracle Critical Patch Update (CPU) April 2026 for Oracle Java SE Services: Java Management Release Date: April 21, 2026

2026-05-23 20:51 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?

2026-05-23 20:51 UTC
Nvd - Cve-2026-43493

web:nvd.nist.gov

An official website of the United States government Here's how you know

2026-05-23 20:51 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 20:51 UTC
Landing Page | ServiceNow Common Vulnerabilities & Exposures (CVE ...

web:support.servicenow.com

Overview The advisories below document publicly disclosed Common Vulnerabilities and Exposures ( CVEs ) in the Now Platform by ServiceNow. Because ServiceNow uses various methods to communicate vulnerability information, patches, and other fixes, customers should review family, security patch , and hotfix release notes, which are available at https://docs.servicenow.com, for a complete list of ...

2026-05-23 20:51 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 20:51 UTC
April 2026 Patch Tuesday: Updates and Analysis | CrowdStrike

web:www.crowdstrike.com

Microsoft's April 2026 Patch Tuesday addresses 164 CVEs , featuring 8 Critical vulnerabilities, one exploited zero-day, and one disclosed zero-day.

2026-05-23 20:51 UTC
Oracle Patches 450 Vulnerabilities With April 2026 CPU

web:www.securityweek.com

Oracle on Tuesday announced the release of 481 new security patches as part of its April 2026 Critical Patch Update (CPU). Across the 28 product families that received security updates, more than 300 patches address vulnerabilities that are remotely exploitable without authentication.

2026-05-23 20:51 UTC
Windows 11 April 2026 Update tested: What's new, improved and fixed

web:www.windowslatest.com

Windows 11 April 2026 update adds Narrator Copilot support, faster Settings, File Explorer fixes, and key security improvements.

2026-05-23 20:51 UTC
April 2026 Critical Patch Update Released | security - Oracle Blogs

web:blogs.oracle.com

For more information about the Critical Patch Update program, see the security vulnerability remediation practices page located on the Oracle Trust Center.

2026-05-26 02:59 UTC
Microsoft Patch Tuesday for April 2026 - Snort Rule and Prominent ...

web:blog.talosintelligence.com

Microsoft has released its monthly security update for April 2026 , which includes 165 vulnerabilities affecting a wide range of products, including eight Microsoft marked as "critical." CVE - 2026 -23666 is a critical Denial of Service (DoS) vulnerability that affects the .NET framework. Successful exploitation could allow the attacker to deny service over the network. CVE - 2026 -32157 is a ...

2026-05-26 02:59 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 .

2026-05-26 02:59 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.

2026-05-26 02:59 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.

2026-05-26 02:59 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.

2026-05-26 02:59 UTC
Microsoft fixes 167 security flaws in April, second biggest Patch ...

web:www.pcworld.com

This month's Patch Tuesday includes an actively exploited Office zero-day vulnerability and several critical RCE bugs in Windows and Remote Desktop.

2026-05-26 02:59 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-43490.json.

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          "programFiles": [
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            },
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            },
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        }
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    "dateReserved": "2026-05-01T14:12:56.012Z",
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