{"id":"CVE-2026-72436","state":"PUBLISHED","title":"netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types","description":"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","publishedAt":"2026-08-15T05:56:50.051Z","updatedAt":"2026-10-16T18:55:24.058Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"c107233d2ff4fd7cef5d02f9124b99194957a710","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"6329d3a9afe715fddda0460cfa46b496d61c2fe0","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"7445fe965b7d8756070a40e80f8b73348ccda1d7","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"c4d257734e91bfcdc71d41843392dd6400b5bb1b","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"3219d74e4536658c937fd878a327257b86ce80dd","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"e4b4984e28c16406ecb318444dea4a8bf47def3e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/ipset/ip_set_hash_gen.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.2","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/ipset/ip_set_hash_gen.h"]}],"references":["https://git.kernel.org/stable/c/c107233d2ff4fd7cef5d02f9124b99194957a710","https://git.kernel.org/stable/c/6329d3a9afe715fddda0460cfa46b496d61c2fe0","https://git.kernel.org/stable/c/7445fe965b7d8756070a40e80f8b73348ccda1d7","https://git.kernel.org/stable/c/c4d257734e91bfcdc71d41843392dd6400b5bb1b","https://git.kernel.org/stable/c/3219d74e4536658c937fd878a327257b86ce80dd","https://git.kernel.org/stable/c/e4b4984e28c16406ecb318444dea4a8bf47def3e"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72436.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72436","state":"PUBLISHED","datePublished":"2026-08-15T05:56:50.051Z","dateUpdated":"2026-10-16T18:55:24.058Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.929Z"},"containers":{"cna":{"title":"netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types","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"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"c107233d2ff4fd7cef5d02f9124b99194957a710","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"6329d3a9afe715fddda0460cfa46b496d61c2fe0","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"7445fe965b7d8756070a40e80f8b73348ccda1d7","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"c4d257734e91bfcdc71d41843392dd6400b5bb1b","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"3219d74e4536658c937fd878a327257b86ce80dd","versionType":"git"},{"version":"18f84d41d34fa35d0d64bbaea01fe664553ecc06","status":"affected","lessThan":"e4b4984e28c16406ecb318444dea4a8bf47def3e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/ipset/ip_set_hash_gen.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.2","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/ipset/ip_set_hash_gen.h"]}],"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"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:44:12.018Z"},"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-72436","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T18:49:57.755944Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T18:55:24.058Z"}}]}}}