Use-after-free in Linux kernel - CVE-2026-63918
Published: July 20, 2026
Vulnerability identifier: #VU138738
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-63918
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 use-after-free.
The vulnerability exists due to a use-after-free in l2tp_session_get_by_ifname() in the l2tp core when looking up a session by interface name during an RCU-protected list walk. A local user can trigger a race condition that returns a session pointer after its reference count has reached zero to cause a use-after-free.
On PREEMPT_RT kernels, the preemption window is real between the interface name comparison and reference count increment.
How to mitigate CVE-2026-63918
Install security update from vendor's repository.