CVE-2026-53389 net/tcp-ao: fix use-after-free of key in del_async path
A use-after-free in the Linux kernel TCP-AO implementation allows attackers to execute code or escalate privileges via crafted socket operations.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53389?
CVE-2026-53389 is a high-severity use after free vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-416
Which versions are affected by CVE-2026-53389?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53389?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-53389 being exploited?
There is no known exploitation of CVE-2026-53389 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-53389, DEBIAN-CVE-2026-53389, GHSA-x37v-hm75-xvf9, UBUNTU-CVE-2026-53389.