Use-after-free in Linux kernel - CVE-2026-43091

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Main Vulnerability Database Vulnerabilities #VU130668

Use-after-free in Linux kernel - CVE-2026-43091

Published: May 7, 2026


Vulnerability identifier: #VU130668
CSH Severity: Low
CVSS v4 BT: 4.3 [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/E:U/U:Clear]
CVE-ID: CVE-2026-43091
CWE-ID: CWE-416
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 use-after-free in xfrm policy_bydst hash tables during network namespace teardown when concurrent RCU-protected policy lookups are performed. A local user can trigger network namespace teardown while the tables are still being accessed to cause a denial of service.

The issue occurs because the memory can be freed before an RCU grace period has elapsed.


Affected software

Linux kernel
openEuler
Ubuntu
bpftool
kernel
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-source
kernel-headers
kernel-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
kernel-tools
kernel-extra-modules
linux (Ubuntu package)
linux-fips (Ubuntu package)
linux-hwe-6.8 (Ubuntu package)
linux-ibm (Ubuntu package)
linux-oracle-6.8 (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-aws-6.8 (Ubuntu package)
linux-aws (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-azure-fde-6.8 (Ubuntu package)
linux-azure (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux-gcp-fips (Ubuntu package)

How to mitigate CVE-2026-43091

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
bpftool - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
kernel - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
python3-perf-debuginfo - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
python3-perf - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
perf-debuginfo - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
perf - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
kernel-tools-devel - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
kernel-tools-debuginfo - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
kernel-source - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
kernel-headers - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
kernel-devel - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
kernel-debugsource - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
kernel-debuginfo - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
bpftool-debuginfo - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
kernel-tools - addressed in versions 5.10.0-318.0.0.221, 6.6.0-145.1.19.156, 6.6.0-145.3.17.150
kernel-extra-modules - update to 6.6.0-145.3.17.150
linux (Ubuntu package) - addressed in versions 6.8.0-136.136, 6.8.0-1046.50, 6.8.0-1059.67, 6.8.0-1064.72, 6.8.0-1064.72~22.04.1, 6.8.1-1056.57, 6.8.1-1056.57~22.04.2
linux-fips (Ubuntu package) - addressed in versions 6.8.0-136.136+fips2, 6.8.0-136.136.2, 6.8.0-136.136.2~22.04.1, 6.8.0-1058.61
linux-hwe-6.8 (Ubuntu package) - update to 6.8.0-136.136~22.04.1
linux-ibm (Ubuntu package) - addressed in versions 6.8.0-1030.31, 6.8.0-1033.34, 6.8.0-1061.62, 6.8.0-1061.62~22.04.1
linux-oracle-6.8 (Ubuntu package) - update to 6.8.0-1058.61~22.04.1
linux-nvidia (Ubuntu package) - addressed in versions 6.8.0-1059.62, 6.8.0-1059.62.1, 6.8.0-1059.62~22.04.1
linux-aws-6.8 (Ubuntu package) - addressed in versions 6.8.0-1061.64+fips1, 6.8.0-1061.64~22.04.1
linux-aws (Ubuntu package) - update to 6.8.0-1061.64+1
linux-azure-fde (Ubuntu package) - update to 6.8.0-1062.69
linux-azure-fde-6.8 (Ubuntu package) - update to 6.8.0-1062.69~22.04.1
linux-azure (Ubuntu package) - addressed in versions 6.8.0-1063.71, 6.8.0-1063.71~22.04.1
linux-azure-fips (Ubuntu package) - update to 6.8.0-1063.71+fips2
linux-gcp-fips (Ubuntu package) - update to 6.8.0-1064.72+fips1

External References

Related Security Bulletins