CVE-2026-68399 bpf: Fix UAF in sock clone early bailouts
A use-after-free in the Linux kernel BPF subsystem allows attackers to execute arbitrary code or escalate privileges via socket cloning.
- 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-2026-68399?
CVE-2026-68399 is a high-severity use after free vulnerability in Linux, published on 10 Aug 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:
bpf: Fix UAF in sock clone early bailouts
Similar to recent commit 9b51a6155d14 ("bpf,fork: wipe ->bpf_storage before bailouts that access it"), sk_clone() performs an initial shallow copy of the socket field ->sk_bpf_storage via sock_copy() for the cloned socket newsk.
If sk_clone() bails out early (e.g. if sk_filter_charge() fails) prior to calling bpf_sk_storage_clone(), newsk->sk_bpf_storage still points to the parent socket's BPF local storage. When newsk is subsequently freed via sk_free(), the deallocation path (__sk_destruct() -> bpf_sk_storage_free()) destroys the parent socket's BPF local storage, leading to a use-after-free (UAF) on the parent socket.
Fix this by resetting newsk->sk_bpf_storage to NULL immediately after sock_copy() in sk_clone(), and remove the now redundant initialization from bpf_sk_storage_clone().
Weakness: CWE-416
Which versions are affected by CVE-2026-68399?
How do I fix CVE-2026-68399?
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-2026-68399 being exploited?
There is no known exploitation of CVE-2026-68399 in the wild and no public exploit code.
Sources
Also known as AZL-94890, BELL-CVE-2026-68399, DEBIAN-CVE-2026-68399, GHSA-f9jq-9v6w-22v9, UBUNTU-CVE-2026-68399.