Skip to main content
VulnerabilityPublished Updated

CVE-2026-89550: Linux kernel · SUNRPC: svcauth_gss: enforce krb5 token minimum length

Affects Linux kernelSource CVE Database V5

0
Compare

Not known to be exploited · CVSS 9.8 Critical · fixed in de942dd8c2c8358bcad04ce44271954c48924423 : patch Linux kernel as a priority.

Data as of 30 Oct 2026, 13:04 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Linux)CVSS 3.19.8
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers can 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 de942dd8c2c8358bcad04ce44271954c48924423, dd6afc6cab8c5d387d1ed2f069562ef7bdadd651, a919c5c88769cf8fb3ec071e6078d830bf512489 +3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Sep 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 30 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 7c9fdcfb1b64c47ed618c103b617af3f86e1239c, < de942dd8c2c8358bcad04ce44271954c48924423
Fixed in
  • de942dd8c2c8358bcad04ce44271954c48924423
LinuxLinuxAffected
  • ≥ 7c9fdcfb1b64c47ed618c103b617af3f86e1239c, < dd6afc6cab8c5d387d1ed2f069562ef7bdadd651
Fixed in
  • dd6afc6cab8c5d387d1ed2f069562ef7bdadd651
LinuxLinuxAffected
  • ≥ 7c9fdcfb1b64c47ed618c103b617af3f86e1239c, < a919c5c88769cf8fb3ec071e6078d830bf512489
Fixed in
  • a919c5c88769cf8fb3ec071e6078d830bf512489
LinuxLinuxAffected
  • ≥ 7c9fdcfb1b64c47ed618c103b617af3f86e1239c, < 2188232509f1559cb8fcb0c9a4b1e04317fa0f15
Fixed in
  • 2188232509f1559cb8fcb0c9a4b1e04317fa0f15
LinuxLinuxAffected
  • ≥ 7c9fdcfb1b64c47ed618c103b617af3f86e1239c, < 2eed1e6a976a44015c3ee78841fe336796e2b21c
Fixed in
  • 2eed1e6a976a44015c3ee78841fe336796e2b21c
LinuxLinuxAffected
  • ≥ 7c9fdcfb1b64c47ed618c103b617af3f86e1239c, < 0ea5b0c7f212c2772d32c2b88287b89a9cdf6edd
Fixed in
  • 0ea5b0c7f212c2772d32c2b88287b89a9cdf6edd

AI-suggested

A fix is available and has been applied in the Linux kernel. The patch adds a minimum length check to reject krb5 tokens that are too short before processing. Users and administrators should update to the fixed Linux kernel versions identified by the commit hashes provided. No additional mitigation is required once the patch is applied.

Description

CVE-2026-89550 is a critical vulnerability in the Linux kernel's SUNRPC svcauth_gss component. It involves improper validation of the minimum length of Kerberos 5 (krb5) tokens, allowing malformed tokens with insufficient length to reach the krb5 unwrap function. This can cause a division by zero error in the rotate_left() function, potentially leading to denial of service or other impacts. The vulnerability is fixed by adding a minimum length check to reject tokens that are too short before processing.

References

Community reviews

Loading reviews…