CVE-2026-53389

In the Linux kernel, the following vulnerability has been resolved:

net/tcp-ao: fix use-after-free of key in del_async path

In tcp_ao_delete_key(), the del_async path skips the current_key and rnext_key validity checks present in the synchronous path, assuming these pointers are always NULL on LISTEN sockets. However, if a key was added with set_current=1/set_rnext=1 while the socket was in CLOSE state, current_key and rnext_key will be non-NULL after listen() transitions the socket to LISTEN.

When such a key is deleted with del_async=1, hlist_del_rcu() and call_rcu() free the key without clearing the dangling pointers. After the RCU grace period, getsockopt(TCP_AO_INFO) dereferences current_key->sndid and rnext_key->rcvid from freed slab memory.

Clear current_key and rnext_key in the del_async path when they reference the key being deleted.

Affected Software

References

• https://git.kernel.org/stable/c/5ba9950bc9078e19b69cca1e56d1553b125c6857
• https://git.kernel.org/stable/c/6ce7ef41743740ce15c2061561b784148b565b3f
• https://git.kernel.org/stable/c/7ddc29a094d96e9b3aa280433c6dc443df9eabf2
• https://git.kernel.org/stable/c/e77fbefd1269b5c123e7c651a1ebdce1b87d19a0