CVE-2026-53239 xfrm: policy: fix use-after-free on inexact bin in xfrm_policy_bysel_ctx()
A race condition in the Linux kernel's xfrm policy handling allows a use-after-free, potentially enabling local attackers to execute code or escalate privileges.
- 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-2026-53239?
CVE-2026-53239 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jun 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:
xfrm: policy: fix use-after-free on inexact bin in xfrm_policy_bysel_ctx()
Fix the race by pruning the bin while still holding xfrm_policy_lock, before dropping it. Use __xfrm_policy_inexact_prune_bin() directly since the lock is already held. The wrapper xfrm_policy_inexact_prune_bin() becomes unused and is removed.
Race:
CPU0 (XFRM_MSG_DELPOLICY) CPU1 (XFRM_MSG_NEWSPDINFO) ========================== ========================== xfrm_policy_bysel_ctx(): spin_lock_bh(xfrm_policy_lock) bin = xfrm_policy_inexact_lookup() __xfrm_policy_unlink(pol) spin_unlock_bh(xfrm_policy_lock) xfrm_policy_kill(ret) // wide window, lock not held xfrm_hash_rebuild(): spin_lock_bh(xfrm_policy_lock) __xfrm_policy_inexact_flush(): kfree_rcu(bin) // bin freed spin_unlock_bh(xfrm_policy_lock) xfrm_policy_inexact_prune_bin(bin) // UAF: bin is freed
Which versions are affected by CVE-2026-53239?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53239?
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-2026-53239 being exploited?
There is no known exploitation of CVE-2026-53239 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-90842, BELL-CVE-2026-53239, DEBIAN-CVE-2026-53239, GHSA-qmj7-fh92-4787, ROOT-OS-DEBIAN-11-CVE-2026-53239, ROOT-OS-DEBIAN-12-CVE-2026-53239 and 3 more.