Use-after-free in Linux kernel - CVE-2026-31669
Published: April 25, 2026
Vulnerability identifier: #VU127731
CSH Severity: Low
CVSS v4.0: 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-2026-31669
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in __inet_lookup_established when performing concurrent ehash lookups on MPTCP IPv6 subflow child sockets under rcu_read_lock. A local user can trigger socket allocation and freeing patterns to cause a denial of service.
The issue affects MPTCP IPv6 subflow child sockets because they may be allocated from a cache without SLAB_TYPESAFE_BY_RCU, allowing freed memory to be reused during lockless lookups.
How to mitigate CVE-2026-31669
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/15fa9ead4d5e6b6b9c794e84144146c917f2cb62
- https://git.kernel.org/stable/c/3fd6547f5b8ac99687be6d937a0321efda760597
- https://git.kernel.org/stable/c/9b55b253907e7431210483519c5ad711a37dafa1
- https://git.kernel.org/stable/c/b313e9037d98c13938740e5ebda7852929366dff
- https://git.kernel.org/stable/c/eb9c6aeb512f877cf397deb1e4526f646c70e4a7
- https://git.kernel.org/stable/c/f6e1f25fa5e733570f6d6fe37a4dfed2a0deba47
- https://git.kernel.org/stable/c/fb1f54b7d16f393b8b65d328410f78b4beea8fcc