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CVE-2026-72436: netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-15 · updated 2026-10-16

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

Affected products

• Linux kernel: 4.2 — fixed in 7.2

How to fix

Upgrade to a fixed version: Linux kernel 7.2. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/3219d74e4536658c937fd878a327257b86ce80dd
• https://git.kernel.org/stable/c/6329d3a9afe715fddda0460cfa46b496d61c2fe0
• https://git.kernel.org/stable/c/7445fe965b7d8756070a40e80f8b73348ccda1d7
• https://git.kernel.org/stable/c/c107233d2ff4fd7cef5d02f9124b99194957a710
• https://git.kernel.org/stable/c/c4d257734e91bfcdc71d41843392dd6400b5bb1b
• https://git.kernel.org/stable/c/e4b4984e28c16406ecb318444dea4a8bf47def3e

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