{"api_version":"1","generated_at":"2026-08-22T09:16:42+00:00","cve":"CVE-2026-72436","urls":{"html":"https://cve.report/CVE-2026-72436","api":"https://cve.report/api/cve/CVE-2026-72436.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-72436","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72436"},"summary":{"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","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:22:17","updated_at":"2026-08-17 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Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72436","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 18f84d41d34fa35d0d64bbaea01fe664553ecc06 c107233d2ff4fd7cef5d02f9124b99194957a710 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 18f84d41d34fa35d0d64bbaea01fe664553ecc06 6329d3a9afe715fddda0460cfa46b496d61c2fe0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 18f84d41d34fa35d0d64bbaea01fe664553ecc06 7445fe965b7d8756070a40e80f8b73348ccda1d7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 18f84d41d34fa35d0d64bbaea01fe664553ecc06 c4d257734e91bfcdc71d41843392dd6400b5bb1b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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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":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"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":{"dateUpdated":"2026-08-17T05:44:12.018Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-72436","datePublished":"2026-08-15T05:56:50.051Z","dateReserved":"2026-08-09T03:40:39.929Z","dateUpdated":"2026-08-17T05:44:12.018Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:22:17","lastModifiedDate":"2026-08-17 06:19:10","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"72436","Ordinal":"1","Title":"netfilter: ipset: Don't use test_bit() in lockless RCU readers i","CVE":"CVE-2026-72436","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"72436","Ordinal":"1","NoteData":"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","Type":"Description","Title":"netfilter: ipset: Don't use test_bit() in lockless RCU readers i"}]}}}