{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72436","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-09T03:40:39.929Z","datePublished":"2026-08-15T05:56:50.051Z","dateUpdated":"2026-08-17T05:44:12.018Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-17T05:44:12.018Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types\n\nSashiko pointed out that there are a few lockless RCU readers\nusing test_bit() which is a relaxed atomic operation and\nprovides no memory barrier guarantees. Use test_bit_acquire()\ninstead where the operation may run parallel with add/del/gc,\ni.e. is not one from the next cases\n\n- protected by region lock\n- in a set destroy phase\n- in a new/temporary set creation phase"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable mtype_test() runs on every packet matched by iptables/nftables xt_set rules in PREROUTING/INPUT/FORWARD, so a remote attacker reaches the bug by sending network traffic to internet-facing servers using ipset-based firewall blocklists.\nAC:L - The attacker controls both sides of the race by flooding packets that trigger lockless RCU readers while concurrently driving hash add/del via SET target rules or timeout GC on the same ipset, making the memory-ordering race reliably winnable.\nPR:N - No credentials or local access are required on the target; exploitation needs only unauthenticated network packets to a host running ipset netfilter rules, a standard deployment on firewalls, mail servers, and CDN edge nodes.\nUI:N - No victim interaction is needed; the attack is fully automated by sending network traffic and does not require mounting filesystems, opening files, or any other user action.\nS:U - The vulnerability corrupts or leaks kernel heap data within the same host security boundary; it does not cross VM, container, or IOMMU isolation boundaries.\nC:H - Without acquire semantics, test_bit() can observe a slot as used before element writes are visible or after deletion, causing reads of uninitialized, stale, or freed hbucket element and extension memory—a UAF-class kernel information disclosure.\nI:H - Stale or torn reads of hash bucket elements during concurrent add/del/gc constitute kernel heap memory safety violations that can corrupt netfilter matching decisions and be further leveraged for control-flow or data manipulation attacks.\nA:H - Reading partially initialized or post-destroy hash element memory during softirq packet processing on loaded firewall datapaths can trigger kernel oopses, panics, or hangs, causing complete loss of availability."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/ipset/ip_set_hash_gen.h"],"versions":[{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","lessThan":"c107233d2ff4fd7cef5d02f9124b99194957a710","status":"affected","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","lessThan":"6329d3a9afe715fddda0460cfa46b496d61c2fe0","status":"affected","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","lessThan":"7445fe965b7d8756070a40e80f8b73348ccda1d7","status":"affected","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","lessThan":"c4d257734e91bfcdc71d41843392dd6400b5bb1b","status":"affected","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","lessThan":"3219d74e4536658c937fd878a327257b86ce80dd","status":"affected","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","lessThan":"e4b4984e28c16406ecb318444dea4a8bf47def3e","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/ipset/ip_set_hash_gen.h"],"versions":[{"version":"4.2","status":"affected"},{"version":"0","lessThan":"4.2","status":"unaffected","versionType":"semver"},{"version":"6.1.178","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.145","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.97","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.40","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.5","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/c107233d2ff4fd7cef5d02f9124b99194957a710"},{"url":"https://git.kernel.org/stable/c/6329d3a9afe715fddda0460cfa46b496d61c2fe0"},{"url":"https://git.kernel.org/stable/c/7445fe965b7d8756070a40e80f8b73348ccda1d7"},{"url":"https://git.kernel.org/stable/c/c4d257734e91bfcdc71d41843392dd6400b5bb1b"},{"url":"https://git.kernel.org/stable/c/3219d74e4536658c937fd878a327257b86ce80dd"},{"url":"https://git.kernel.org/stable/c/e4b4984e28c16406ecb318444dea4a8bf47def3e"}],"title":"netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types","x_generator":{"engine":"bippy-1.2.0"}}}}