Skip to main content
VulnerabilityPublished Updated

CVE-2026-43091: Linux kernel · Use After Free

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in b66920a3348c0f63ba18365248fa21fbf0b3a937 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in b66920a3348c0f63ba18365248fa21fbf0b3a937, 3733fce2871c9bca9dd18a1a23b1432ea215a094, 438b1f668ad58f46ce699bb48e4698a7839e3f9e +2
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 6 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ e1e551bc56302b80ff930c966f9985095fb1b70d, < b66920a3348c0f63ba18365248fa21fbf0b3a937
Fixed in
  • b66920a3348c0f63ba18365248fa21fbf0b3a937
LinuxLinuxAffected
  • ≥ e1e551bc56302b80ff930c966f9985095fb1b70d, < 3733fce2871c9bca9dd18a1a23b1432ea215a094
Fixed in
  • 3733fce2871c9bca9dd18a1a23b1432ea215a094
LinuxLinuxAffected
  • ≥ e1e551bc56302b80ff930c966f9985095fb1b70d, < 438b1f668ad58f46ce699bb48e4698a7839e3f9e
Fixed in
  • 438b1f668ad58f46ce699bb48e4698a7839e3f9e
LinuxLinuxAffected
  • ≥ e1e551bc56302b80ff930c966f9985095fb1b70d, < 069daad4f2ae9c5c108131995529d5f02392c446
Fixed in
  • 069daad4f2ae9c5c108131995529d5f02392c446
LinuxLinuxAffected
  • ≥ e1e551bc56302b80ff930c966f9985095fb1b70d, < 33a3149dd81a1e2f52b80ee1e0fc380b39f3d028
Fixed in
  • 33a3149dd81a1e2f52b80ee1e0fc380b39f3d028
LinuxLinuxAffected
  • =4.9
Fixed in–

AI-suggested

A fix is available and has been applied in specific commits identified by their hashes. Users should update their Linux kernel to a version that includes these fixes to mitigate the vulnerability. Since this is a kernel-level issue, patching the kernel is the recommended remediation.

Description

CVE-2026-43091 is a use-after-free vulnerability in the Linux kernel's xfrm subsystem related to policy netns exit. The flaw occurs because the kernel does not wait for concurrent RCU readers to finish before freeing policy hash tables, potentially leading to memory corruption. This issue has been fixed by adding an RCU grace period synchronization before freeing the tables.

References

Community reviews

Loading reviews…