{"id":"CVE-2026-72418","title":"netfilter: nf_conncount: prevent connlimit drops for early confirmed ct","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conncount: prevent connlimit drops for early confirmed ct\n\nCommit 69894e5b4c5e (\"netfilter: nft_connlimit: update the count if add\nwas skipped\") introduce…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 460c112e1d887b58b06b56e8e0230058906ff2c3 < 000ac6830b56499d6b65fd91486ce6689eb02be4","Linux >= 53bc0ac47f4f7621c991807bc90e01df49561ac8 < cbe2d14a7c5b1fc71821fbfee5c4963917411e92","Linux >= ca8b4d1d6304a84ce2016fa2fe9a114b9607b839 < 3793d24de224943e0a6016bbeffb6f5c4cea2e3d","Linux >= 8286c02fe9100330475331253fc590f047963f90 < abef7f817217fcb62c11821d6b895063eadb2828","Linux >= b29ddccf36946a90323486221f39e9f88cc01b8e < ebfe8249ba79e4ff0f1e3aad8787b992ef27f026","Linux >= 77ea3d8ac3d3d59b5ac9ad639e4ba107c0f2ff1e < 329f2626ee5cb8fafdf6b58b624311529c57cb45","Linux >= 69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e < be52572c6d55f677ba76869d3c63805c0d4891a3","Linux >= 69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e < c8b6f36f766991e3ebebec6596daee4b04dcbc49","Linux f85623af16b83615e5f64a9b19ae1d584805cb07","Linux >= 5.10.248 < 5.10.261","Linux >= 5.15.198 < 5.15.212","Linux >= 6.1.160 < 6.1.178","Linux >= 6.6.120 < 6.6.145","Linux >= 6.12.63 < 6.12.97","Linux >= 6.18.2 < 6.18.40","Linux >= 6.17.13 < 6.18","Linux 6.19"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-16T18:49:23.434729Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:55:22.660Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72418","references":[{"url":"https://git.kernel.org/stable/c/000ac6830b56499d6b65fd91486ce6689eb02be4"},{"url":"https://git.kernel.org/stable/c/cbe2d14a7c5b1fc71821fbfee5c4963917411e92"},{"url":"https://git.kernel.org/stable/c/3793d24de224943e0a6016bbeffb6f5c4cea2e3d"},{"url":"https://git.kernel.org/stable/c/abef7f817217fcb62c11821d6b895063eadb2828"},{"url":"https://git.kernel.org/stable/c/ebfe8249ba79e4ff0f1e3aad8787b992ef27f026"},{"url":"https://git.kernel.org/stable/c/329f2626ee5cb8fafdf6b58b624311529c57cb45"},{"url":"https://git.kernel.org/stable/c/be52572c6d55f677ba76869d3c63805c0d4891a3"},{"url":"https://git.kernel.org/stable/c/c8b6f36f766991e3ebebec6596daee4b04dcbc49"}],"tags":["cve.org"],"epss":0.00716,"epssPercentile":0.52837,"ingestedAt":"2026-10-16T19:46:24.398Z","slug":"CVE-2026-72418","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conncount: prevent connlimit drops for early confirmed ct\n\nCommit 69894e5b4c5e (\"netfilter: nft_connlimit: update the count if add\nwas skipped\") introduced a regression where packets for valid\nconnections are dropped when using connlimit for soft-limiting\nscenarios.\n\nThe issue occurs when a new connection reuses a socket currently in\nthe TIME_WAIT state. In this scenario, the connection tracking entry\nis evaluated as already confirmed. Previously, __nf_conncount_add()\nassumed that if a connection was confirmed and did not originate from\nthe loopback interface, it should skip the addition and return -EEXIST.\n\nSkipping the addition triggers a garbage collection run that cleans up\nthe TIME_WAIT connection. Consequently, the active connection count\ndrops to 0, which xt_connlimit mishandles, leading to the false rejection\nof the perfectly valid new connection.\n\nFix this by replacing the interface check with protocol-agnostic state\nchecks. We now skip the tree insertion and preserve the lockless garbage\ncollection optimization only if the connection is IPS_ASSURED. This\nallows early-confirmed setup packets (such as reused TIME_WAIT sockets\nor locally generated SYN-ACKs) to be properly evaluated and counted\nwithout falsely dropping. The goto check_connections path is maintained\nto ensure these setup packets are deduplicated correctly.\n\nThis has been tested with slowhttptest and HTTP server configured\nlocally to ensure we are not breaking soft-limiting scenarios for local\nor external connections. In addition, it was tested with a OVS zone\nlimit too.\n\n## Affected\n\n- `Linux >= 460c112e1d887b58b06b56e8e0230058906ff2c3 < 000ac6830b56499d6b65fd91486ce6689eb02be4`\n- `Linux >= 53bc0ac47f4f7621c991807bc90e01df49561ac8 < cbe2d14a7c5b1fc71821fbfee5c4963917411e92`\n- `Linux >= ca8b4d1d6304a84ce2016fa2fe9a114b9607b839 < 3793d24de224943e0a6016bbeffb6f5c4cea2e3d`\n- `Linux >= 8286c02fe9100330475331253fc590f047963f90 < abef7f817217fcb62c11821d6b895063eadb2828`\n- `Linux >= b29ddccf36946a90323486221f39e9f88cc01b8e < ebfe8249ba79e4ff0f1e3aad8787b992ef27f026`\n- `Linux >= 77ea3d8ac3d3d59b5ac9ad639e4ba107c0f2ff1e < 329f2626ee5cb8fafdf6b58b624311529c57cb45`\n- `Linux >= 69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e < be52572c6d55f677ba76869d3c63805c0d4891a3`\n- `Linux >= 69894e5b4c5e28cda5f32af33d4a92b7a4b93b0e < c8b6f36f766991e3ebebec6596daee4b04dcbc49`\n- `Linux f85623af16b83615e5f64a9b19ae1d584805cb07`\n- `Linux >= 5.10.248 < 5.10.261`\n- `Linux >= 5.15.198 < 5.15.212`\n- `Linux >= 6.1.160 < 6.1.178`\n- `Linux >= 6.6.120 < 6.6.145`\n- `Linux >= 6.12.63 < 6.12.97`\n- `Linux >= 6.18.2 < 6.18.40`\n- `Linux >= 6.17.13 < 6.18`\n- `Linux 6.19`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}