SB20260720106 - Race condition in Linux kernel l2tp

Description

This security bulletin contains information about 1 vulnerability.

1) Race condition (CVE-ID: CVE-2026-64119)

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSSv4: 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]

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

The vulnerability exists due to improper concurrent modification of an rcu-protected list in l2tp_session_unhash() when handling concurrent L2TP session get, create, and delete operations on the same tunnel. A local user can issue crafted concurrent netlink commands to cause a denial of service.

Exploitation can pin a host CPU indefinitely and stall RCU grace periods, and the issue is reachable from a standard unshare sandbox when l2tp_core is loaded.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/5e40919a40cb3e590ed45c2a54a4a2518aa88a99
• https://git.kernel.org/stable/c/979c017803c40829b03acd9e5236e354b7622360
• https://git.kernel.org/stable/c/acab6314bb75be994f720ed13e9d9139cbf828a8
• https://git.kernel.org/stable/c/e0c3dd7b30cc5ee42ab502da140cda93d794a20b