Time-of-check Time-of-use (TOCTOU) Race Condition in Linux kernel - CVE-2026-64091

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Main Vulnerability Database Vulnerabilities #VU138554

Time-of-check Time-of-use (TOCTOU) Race Condition in Linux kernel - CVE-2026-64091

Published: July 20, 2026


Vulnerability identifier: #VU138554
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64091
CWE-ID: CWE-367
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to a race condition leading to an out-of-bounds write in batadv_tt_prepare_tvlv_local_data in the batman-adv translation table handling when generating local TT TVLV data for reported VLANs. A local user can trigger concurrent VLAN translation table entry changes to cause a denial of service.

The issue arises from a time-of-check time-of-use condition where the number of non-empty VLANs can increase after buffer sizing but before the buffer is filled.


Affected software

Linux kernel
Ubuntu
linux-aws (Ubuntu package)
linux (Ubuntu package)
linux-fips (Ubuntu package)
linux-nvidia-tegra (Ubuntu package)
linux-nvidia-tegra-5.15 (Ubuntu package)
linux-ibm-5.15 (Ubuntu package)
linux-aws-5.15 (Ubuntu package)
linux-oracle-5.15 (Ubuntu package)
linux-gcp-5.15 (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-aws-fips (Ubuntu package)
linux-ibm (Ubuntu package)
linux-azure (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

How to mitigate CVE-2026-64091

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-aws (Ubuntu package) - addressed in versions 5.15.0-194.204~20.04.1, 5.15.0-194.204, 5.15.0-1079.83, 5.15.0-1099.107, 5.15.0-1108.110, 5.15.0-1108.113, 5.15.0-1110.114, 5.15.0-1111.117, 5.15.0-1112.118, 5.15.0-1113.119, 5.15.0-1115.124, 5.15.0-1116.123, 5.15.0-1116.123+fips1, 5.15.0-1116.126+fips1, 5.15.0-1117.127, 5.15.0-1121.130, 5.15.0-1122.131, 5.15.0-1122.131+fips1, 5.15.0.194.159, 5.15.0.1079.82, 5.15.0.1099.98, 5.15.0.1108.104, 5.15.0.1108.112, 5.15.0.1110.107, 5.15.0.1111.110, 5.15.0.1112.111, 5.15.0.1113.109, 5.15.0.1115.119, 5.15.0.1116.106, 5.15.0.1116.112, 5.15.0.1116.119, 5.15.0.1117.114, 5.15.0.1122.106, 5.15.0.1122.120, 6.8.0-1065.68~22.04.1, 6.8.0-1065.68, 7.0.0-1009.9, 7.0.0-1015.15
linux (Ubuntu package) - addressed in versions 5.15.0-194.204, 5.15.0-1111.112, 5.15.0.194.171, 5.15.0.1111.111, 6.8.0-142.142+fips1, 6.8.0-142.142.1~22.04.1, 6.8.0-142.142.1, 6.8.0-1050.54, 6.8.0-1062.65~22.04.1, 6.8.0-1064.72+fips1, 6.8.0-1065.66, 6.8.0-1065.69, 6.8.0-1066.73~22.04.1, 6.8.0-1066.73, 6.8.0-1068.76~22.04.1, 6.8.0-1068.76, 6.8.0-1068.76+fips1, 6.8.0-1069.77~22.04.1, 6.8.0-1069.77, 6.8.0-2054.56, 6.8.1-1060.61~22.04.1, 6.8.1-1060.61
linux-fips (Ubuntu package) - addressed in versions 5.15.0-194.204+fips1, 5.15.0.194.113
linux-nvidia-tegra (Ubuntu package) - addressed in versions 5.15.0-1057.57, 5.15.0-1068.70, 5.15.0.1057.59, 5.15.0.1068.68, 6.8.0-1035.38
linux-nvidia-tegra-5.15 (Ubuntu package) - update to 5.15.0-1068.70~20.04.1
linux-ibm-5.15 (Ubuntu package) - update to 5.15.0-1110.114~20.04.1
linux-aws-5.15 (Ubuntu package) - addressed in versions 5.15.0-1111.117~20.04.1, 5.15.0-1116.123~20.04.1, 5.15.0-1121.130~20.04.1, 5.15.0-1122.131~20.04.1
linux-oracle-5.15 (Ubuntu package) - addressed in versions 5.15.0-1114.120~20.04.1, 5.15.0.1114.120~20.04.1
linux-gcp-5.15 (Ubuntu package) - addressed in versions 5.15.0-1118.128~20.04.1, 5.15.0.1118.128~20.04.1
linux-nvidia (Ubuntu package) - addressed in versions 6.8.0-1063.66~22.04.1, 6.8.0-1063.66, 6.8.0-1063.66.1, 7.0.0-1016.16~24.04.1, 7.0.0-1016.16
linux-aws-fips (Ubuntu package) - update to 6.8.0-1065.68+fips1
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-azure-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

External References

Related Security Bulletins