CVE-2026-64091: Linux kernel · batman-adv: tt: fix TOCTOU race for reported vlans
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 5.15.0-1116.123~20.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 15:59 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 36% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1116.123~20.04.1, 5.15.0-1122.131~20.04.1, 5.15.0-1121.130~20.04.1 +69
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 20 Jul 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
Upgrade to a fixed release listed under Affected software.
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
An official patch is available and should be applied promptly. The vendor advisory confirms that this issue has been fixed in updated linux-aws kernel packages. Users should update to the fixed kernel versions as per their distribution's guidance.
Description
A time-of-check to time-of-use (TOCTOU) race condition vulnerability was identified and fixed in the batman-adv tt subsystem of the Linux kernel. The issue involved incorrect buffer size allocation for VLAN entries due to changes in the number of TT entries during processing. This could lead to buffer overflows or memory corruption. The vulnerability affects multiple linux-aws kernel versions and has a high severity with a CVSS score of 9.8. Official patches are available to address this flaw.
References
- nvd.nist.gov/vuln/detail/CVE-2026-64091 (opens in a new tab)
- git.kernel.org/stable/c/211ea59988e1cba43cb0367ad65d379b56f9c3bd (opens in a new tab)
- git.kernel.org/stable/c/4cc85aec8d3c9ab4dc716dc9f1ed36fca16b227f (opens in a new tab)
- git.kernel.org/stable/c/65a1e67339aa8c95ac544b796946af388930ee23 (opens in a new tab)
- git.kernel.org/stable/c/724a8eb4155669797c96b70d70e354284ae3b5a8 (opens in a new tab)
- git.kernel.org/stable/c/94d27005016be15ffc638b2ecbc4d58805ad7b48 (opens in a new tab)
- git.kernel.org/stable/c/9a9c859457bc440a55773e01ff18b1bb5bab6836 (opens in a new tab)
- git.kernel.org/stable/c/b4d4efd4e351593c81e9293d4b4408d244fa5ee7 (opens in a new tab)
- git.kernel.org/stable/c/e4236bf3ec8d6bb15d0d8d825dcf9933a7d6666b (opens in a new tab)
- ubuntu.com/security/CVE-2026-64091 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-64091 (opens in a new tab)
- git.kernel.org/linus/94d27005016be15ffc638b2ecbc4d58805ad7b48 (opens in a new tab)
- ubuntu.com/security/notices/USN-8593-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8603-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8618-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8663-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8664-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8781-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8817-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8818-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8818-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8842-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8818-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8818-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8817-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8849-1 (opens in a new tab)