CVE-2026-45918
Published: May 27, 2026· Updated: May 27, 2026
Official Description
In the Linux kernel, the following vulnerability has been resolved:
ovpn: tcp - don't deref NULL sk_socket member after tcp_close()
When deleting a peer in case of keepalive expiration, the peer is
removed from the OpenVPN hashtable and is temporary inserted in a
"release list" for further processing.
This happens in:
ovpn_peer_keepalive_work()
unlock_ovpn(release_list)
This processing includes detaching from the socket being used to
talk to this peer, by restoring its original proto and socket
ops/callbacks.
In case of TCP it may happen that, while the peer is sitting in
the release list, userspace decides to close the socket.
This will result in a concurrent execution of:
tcp_close(sk)
__tcp_close(sk)
sock_orphan(sk)
sk_set_socket(sk, NULL)
The last function call will set sk->sk_socket to NULL.
When the releasing routine is resumed, ovpn_tcp_socket_detach()
will attempt to dereference sk->sk_socket to restore its original
ops member. This operation will crash due to sk->sk_socket being NULL.
Fix this race condition by testing-and-accessing
sk->sk_socket atomically under sk->sk_callback_lock.
Technical Analysis
CVE-2026-45918 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
Affected Vendors & Products
Exploit & PoC Resources
All References (3)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-45918 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts