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VulnerabilityPublished Updated

CVE-2026-31636: Linux kernel · rxrpc: fix RESPONSE authenticator parser OOB read

Affects Linux kernelSource GCVE Database

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Authoritative record:CVE-2026-31636· Critical 9.1

Not known to be exploited · CVSS 9.1 Critical · fixed in 6.17.0-1022.22 : patch Linux kernel as a priority.

Data as of 12 Nov 2026, 19:39 UTC

CVSS 3.1 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Linux)CVSS 3.19.1
Patch
Available – fixed in 6.17.0-1022.22, 6.17.0-1022.25, 6.17.0-42.42 +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: 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 12 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSlinux-nvidiapkg:deb/ubuntu/linux-nvidia?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-1006.6
Fixed in
  • 7.0.0-1006.6
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threatsAffected
  • 6.14.0-15.15 – 6.17.0-40.40
20 affected builds
Fixed in–
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1005.5 – 6.17.0-1019.19
17 affected builds
Fixed in–
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1004.4 – 6.17.0-1020.20
16 affected builds
Fixed in–
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threatsAffected
  • 6.17.0-1003.3 – 6.17.0-1017.17
10 affected builds
Fixed in–
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1006.6 – 6.17.0-1020.22
17 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and should be applied promptly. Ubuntu has released fixed kernel packages including versions 6.17.0-1022.22 and later. After applying the update, a system reboot is required to activate the fix. Due to an ABI change, all third-party kernel modules must be recompiled and reinstalled. Follow the vendor advisories USN-8636-1 and USN-8636-2 for detailed update instructions. No additional mitigations are indicated.

Description

CVE-2026-31636 is a critical vulnerability in the Linux kernel's rxrpc subsystem involving an out-of-bounds read in the RESPONSE authenticator parser. The flaw arises because the rxgk_verify_authenticator() function incorrectly calculates the parser limit, allowing malformed RESPONSE authenticators to read beyond the allocated buffer. This issue has been fixed in Linux kernel versions 6.17.0-1022.22 and later. The vulnerability has a CVSS score of 9.1, indicating high severity with potential for system impact. Ubuntu has released security updates addressing this flaw across multiple kernel packages, requiring system reboot and recompilation of third-party kernel modules due to ABI changes.

References

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