CVE-2026-72463 xfrm: Fix dev use-after-free in xfrm async resumption
A use-after-free vulnerability in the Linux kernel's xfrm subsystem allows attackers to cause denial of service or potentially execute code via race conditions during async resumption.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72463?
CVE-2026-72463 is a critical use after free vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
xfrm: Fix dev use-after-free in xfrm async resumption
xfrm async resumption hold skb->dev refcnt until after transport_finish. However, xfrm_rcv_cb may modify skb->dev to tunnel dev without taking device reference, such as vti_rcv_cb. The subsequent async resumption will decrement the tunnel device's reference count, which lead to uaf of tunnel dev and refcnt leak of orig dev as below:
unregister_netdevice: waiting for vti1 to become free. Usage count = -2
Stash the original skb->dev to fix refcnt imbalance. The new skb->dev set by xfrm_rcv_cb can race with device teardown. Extend rcu protection over xfrm_rcv_cb and transport_finish to prevent races.
Which versions are affected by CVE-2026-72463?
How do I fix CVE-2026-72463?
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-2026-72463 being exploited?
There is no known exploitation of CVE-2026-72463 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72463, DEBIAN-CVE-2026-72463, GHSA-23r2-6gqr-3m38, UBUNTU-CVE-2026-72463.