CVE-2026-89555: Linux kernel · mpls: reload header after pskb_may_pull()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 52% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 11 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| 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 fix has been implemented to reload the header pointer after each pskb_may_pull() call to prevent use-after-free. Users should apply the official patches or upgrade to fixed kernel versions. Check vendor advisories for the latest patched versions and update accordingly.
Description
A use-after-free vulnerability in the Linux kernel's MPLS multipath code was resolved. The issue occurs when the kernel reloads the header after pskb_may_pull() calls in mpls_select_multipath(), leading to a stale pointer referencing freed memory. This was detected via static analysis and confirmed by a KASAN report triggered by a specific packet setup. The flaw affects multiple specific Linux Azure kernel versions.
References
- nvd.nist.gov/vuln/detail/CVE-2026-89555 (opens in a new tab)
- git.kernel.org/stable/c/29e63b8d9fc150cc191b1c6eb7e16e1247e1b650 (opens in a new tab)
- git.kernel.org/stable/c/49d38c1b4390412f8950d33dfaee0ccbd17beb81 (opens in a new tab)
- git.kernel.org/stable/c/d82b90a38c2ca8a0694428eab0e9551c23f2447d (opens in a new tab)
- git.kernel.org/stable/c/fed638a248116b8a249bd4202d28e5934bdc65ad (opens in a new tab)
- ubuntu.com/security/CVE-2026-89555 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89555 (opens in a new tab)
- git.kernel.org/linus/29e63b8d9fc150cc191b1c6eb7e16e1247e1b650 (opens in a new tab)