CVE-2026-53239

Summary

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

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/8fc536e9f6856230f19c7d13e71af064b6a77b22
• https://git.kernel.org/stable/c/c4c1ea36d83bf3c4569468ca5b8b614fda1bf821
• https://git.kernel.org/stable/c/25c8c7fb3b0b9668c7d05e209f58c158d2b020c7
• https://git.kernel.org/stable/c/42827d03f8009a6a218bacab153e21f39d6a121c
• https://git.kernel.org/stable/c/88697cf980222d5906a37bf47662dac0732e2a0f
• https://git.kernel.org/stable/c/b5316e2b8614a87d8736941972441cb47bfd4491
• https://git.kernel.org/stable/c/ec82ea4eb220164d854f8734ca5a35e23e577b94
• https://git.kernel.org/stable/c/7f2d76c9c03257c0782afef9d95321fa04096f60

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