Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types Sashiko pointed out that there are a few lockless RCU readers using test_bit() which is a relaxed atomic operation and provides no memory barrier guarantees. Use test_bit_acquire() instead where the operation may run parallel with add/del/gc, i.e. is not one from the next cases - protected by region lock - in a set destroy phase - in a new/temporary set creation phase
References6
- git.kernel.org/stable/c/3219d74e4536658c937fd878a327257b86ce80dd
- git.kernel.org/stable/c/6329d3a9afe715fddda0460cfa46b496d61c2fe0
- git.kernel.org/stable/c/7445fe965b7d8756070a40e80f8b73348ccda1d7
- git.kernel.org/stable/c/c107233d2ff4fd7cef5d02f9124b99194957a710
- git.kernel.org/stable/c/c4d257734e91bfcdc71d41843392dd6400b5bb1b
- git.kernel.org/stable/c/e4b4984e28c16406ecb318444dea4a8bf47def3e
Metrics
- CVSS 3.1
-
9.8
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 1% percentile: 54 · as of 11 November 2026
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.