{"id":"CVE-2026-52920","state":"PUBLISHED","title":"netfilter: xt_policy: fix strict mode inbound policy matching","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_policy: fix strict mode inbound policy matching\n\nmatch_policy_in() walks sec_path entries from the last transform to the\nfirst one, but strict policy matching needs to consume info->pol[] in\nthe same forward order as the rule layout.\n\nDerive the strict-match policy position from the number of transforms\nalready consumed so that multi-element inbound rules are matched\nconsistently.","publishedAt":"2026-06-24T07:14:15.866Z","updatedAt":"2026-10-19T19:37:00.676Z","severity":{"score":8.3,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"eb323f7b82d2e2f638de0cc2a177803eb20e0707","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"fc1c518bb1f054831ecabb32da9b8e1dff9699c6","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"f98b7f85e04b40e28b08c461ded0cc79f14f5509","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"82664d0f1ba25e4f9a71994954abae24c60f4067","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"b130a6eefa02bd4d475f2f059da8bcfb3e7d18d9","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"938867e870fb5471bb16f442aeac81326e05bf65","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"392cc1d8408b5665215c1e9290bbf0f92339b043","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"4b2b4d7d4e203c92db8966b163edfacb1f0e1e29","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/xt_policy.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.17","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.141","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.91","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.33","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.10","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/xt_policy.c"]}],"references":["https://git.kernel.org/stable/c/eb323f7b82d2e2f638de0cc2a177803eb20e0707","https://git.kernel.org/stable/c/fc1c518bb1f054831ecabb32da9b8e1dff9699c6","https://git.kernel.org/stable/c/f98b7f85e04b40e28b08c461ded0cc79f14f5509","https://git.kernel.org/stable/c/82664d0f1ba25e4f9a71994954abae24c60f4067","https://git.kernel.org/stable/c/b130a6eefa02bd4d475f2f059da8bcfb3e7d18d9","https://git.kernel.org/stable/c/938867e870fb5471bb16f442aeac81326e05bf65","https://git.kernel.org/stable/c/392cc1d8408b5665215c1e9290bbf0f92339b043","https://git.kernel.org/stable/c/4b2b4d7d4e203c92db8966b163edfacb1f0e1e29"],"weaknesses":["CWE-682"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/52xxx/CVE-2026-52920.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-52920","state":"PUBLISHED","datePublished":"2026-06-24T07:14:15.866Z","dateUpdated":"2026-10-19T19:37:00.676Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.367Z"},"containers":{"cna":{"title":"netfilter: xt_policy: fix strict mode inbound policy matching","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_policy: fix strict mode inbound policy matching\n\nmatch_policy_in() walks sec_path entries from the last transform to the\nfirst one, but strict policy matching needs to consume info->pol[] in\nthe same forward order as the rule layout.\n\nDerive the strict-match policy position from the number of transforms\nalready consumed so that multi-element inbound rules are matched\nconsistently."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"eb323f7b82d2e2f638de0cc2a177803eb20e0707","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"fc1c518bb1f054831ecabb32da9b8e1dff9699c6","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"f98b7f85e04b40e28b08c461ded0cc79f14f5509","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"82664d0f1ba25e4f9a71994954abae24c60f4067","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"b130a6eefa02bd4d475f2f059da8bcfb3e7d18d9","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"938867e870fb5471bb16f442aeac81326e05bf65","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"392cc1d8408b5665215c1e9290bbf0f92339b043","versionType":"git"},{"version":"c4b885139203d37f76662c37ae645fe8e0f4e4e5","status":"affected","lessThan":"4b2b4d7d4e203c92db8966b163edfacb1f0e1e29","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/xt_policy.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.17","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.141","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.91","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.33","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.10","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/xt_policy.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/eb323f7b82d2e2f638de0cc2a177803eb20e0707"},{"url":"https://git.kernel.org/stable/c/fc1c518bb1f054831ecabb32da9b8e1dff9699c6"},{"url":"https://git.kernel.org/stable/c/f98b7f85e04b40e28b08c461ded0cc79f14f5509"},{"url":"https://git.kernel.org/stable/c/82664d0f1ba25e4f9a71994954abae24c60f4067"},{"url":"https://git.kernel.org/stable/c/b130a6eefa02bd4d475f2f059da8bcfb3e7d18d9"},{"url":"https://git.kernel.org/stable/c/938867e870fb5471bb16f442aeac81326e05bf65"},{"url":"https://git.kernel.org/stable/c/392cc1d8408b5665215c1e9290bbf0f92339b043"},{"url":"https://git.kernel.org/stable/c/4b2b4d7d4e203c92db8966b163edfacb1f0e1e29"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H","baseScore":8.3,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable matcher is executed while processing inbound IPv4/IPv6 packets through x_tables after XFRM/IPsec has populated the packet sec_path. A remote IPsec peer can trigger the affected strict inbound policy rule by sending network packets in a realistic VPN/gateway deployment.\nAC:L - Exploitation requires a strict inbound xt_policy rule with multiple policy elements and a packet with the same number of transforms, but those are normal affected configurations rather than attacker-uncontrolled races. Once present, triggering is repeatable by sending matching packets.\nPR:L - Unauthenticated packets generally fail XFRM state/authentication before reaching this sec_path-based match, so the network scenario requires an authorized IPsec peer or equivalent low privilege. Locally, the rule/XFRM setup is gated by CAP_NET_ADMIN in the network namespace, which is reachable through user namespaces.\nUI:N - No victim user action is needed after the vulnerable rule/state configuration exists. Packet delivery or local namespace traffic is sufficient to invoke the matcher.\nS:U - The bug is in kernel netfilter/XFRM policy evaluation and impacts the same kernel/network security authority. It does not cross a VM, IOMMU, or separate sandbox security scope.\nC:H - The old strict inbound index calculation can make pos negative and read before info->pol[], including x_tables rule metadata or adjacent kernel allocation contents. Although exposed through match behavior rather than a direct copy_to_user, this is an out-of-bounds kernel read larger than a few bytes, so the higher confidentiality impact is warranted.\nI:L - The bug does not provide a direct write primitive or code execution path, but it can make strict IPsec policy matching produce incorrect firewall decisions. That can bypass or misapply intended packet filtering for affected multi-element inbound rules.\nA:H - The negative-index read can reach outside the intended match data and, for larger strict transform counts or unlucky layout, may fault/oops in kernel packet processing. The condition can be triggered repeatedly with packets once the affected rule path is reachable."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:31:42.384Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"5.10.258"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"5.15.209"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"6.6.141"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"6.12.91"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"6.18.33"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"7.0.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.17","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-52920","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:22:43.940602Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-682","lang":"en","type":"CWE","description":"CWE-682 Incorrect Calculation"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:37:00.676Z"}}]}}}