CVE-2026-43490: In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate inherited ACE SID length

Q: How do I fix CVE-2026-43490?

linux kernel: upgrade to 6.6.141, 6.12.88, 6.18.30, 7.0.7. Exact commands for each OS are on this page.

Q: Is CVE-2026-43490 being exploited?

CVE-2026-43490 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-43490 affect?

CVE-2026-43490 affects linux kernel. Severity is high (CVSS 8.8). 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

Q: How urgent is CVE-2026-43490?

Priority 45/100. High severity; On your watchlist

This month

HIGH 8.8WATCHLISTUPGRADE

CVE-2026-43490 is a high-severity flaw (CVSS 8.8) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 65%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-05-15
Last modified	2026-06-26

Publisher (CNA): kernel.org · Vendor: linux

Last updated 2026-06-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-15 06:16 UTCPublished CVE record published
2026-06-26 19:16 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 5.15 and < 6.6.141 · >= 6.7 and < 6.12.88 · >= 6.13 and < 6.18.30 · >= 6.19 and < 7.0.7 · 7.1 rc1 · 7.1 rc2

Fixed in: 6.6.141, 6.12.88, 6.18.30, 7.0.7

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-43490?

linux kernel: upgrade to 6.6.141, 6.12.88, 6.18.30, 7.0.7. Exact commands for each OS are on this page.

Is CVE-2026-43490 being exploited?

CVE-2026-43490 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-43490 affect?

CVE-2026-43490 affects linux kernel. Severity is high (CVSS 8.8). 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

How urgent is CVE-2026-43490?

Priority 45/100. High severity; On your watchlist

Software pages

Linux kernel vulnerabilities

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References

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