CVE-2026-53239

xfrm: policy: fix use-after-free on inexact bin in xfrm_policy_bysel_ctx()

HIGH

7.8

CVSS Score

Published: June 25, 2026 at 08:39 AM UTC

Updated: October 19, 2026 at 08:19 PM UTC

4 products affected across 2 vendorsLinux KernelSIMATIC S7-1500 CPU 1518-4 Pn /dp MFP FirmwareSiplus S7-1500 CPU 1518-4 Pn /dp MFP Firmware

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Severity

HIGH7.8

Exploit prediction

EPSS 0.1%

SSVC

No known exploit

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

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel · Linux

95%

5.0 ≤ v < 5.10.2595.11 ≤ v < 5.15.2105.16 ≤ v < 6.1.1766.13 ≤ v < 6.18.366.19 ≤ v < 7.0.136.2 ≤ v < 6.6.1436.7 ≤ v < 6.12.946be3b0db6db82cf056a72cc18042048edd27f8ee7.1 7.1 rc1 7.1 rc2 7.1 rc3 7.1 rc4 7.1 rc5 7.1 rc6 7.1 rc7

Vendor states this is fixed in 25c8c7fb3b0b9668c7d05e209f58c158d2b020c7 (fixed)

Vendor states this is fixed in 42827d03f8009a6a218bacab153e21f39d6a121c (fixed)

Vendor states this is fixed in 7f2d76c9c03257c0782afef9d95321fa04096f60 (fixed)

Vendor states this is fixed in 88697cf980222d5906a37bf47662dac0732e2a0f (fixed)

Vendor states this is fixed in 8fc536e9f6856230f19c7d13e71af064b6a77b22 (fixed)

Vendor states this is fixed in b5316e2b8614a87d8736941972441cb47bfd4491 (fixed)

Vendor states this is fixed in c4c1ea36d83bf3c4569468ca5b8b614fda1bf821 (fixed)

Vendor states this is fixed in ec82ea4eb220164d854f8734ca5a35e23e577b94 (fixed)

Vendor states this is fixed in 5.0 (unaffected)

Vendor states this is fixed in 5.10.259 (unaffected)

Vendor states this is fixed in 5.15.210 (unaffected)

Vendor states this is fixed in 6.1.176 (unaffected)