{"id":"CVE-2026-31681","state":"PUBLISHED","title":"netfilter: xt_multiport: validate range encoding in checkentry","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_multiport: validate range encoding in checkentry\n\nports_match_v1() treats any non-zero pflags entry as the start of a\nport range and unconditionally consumes the next ports[] element as\nthe range end.\n\nThe checkentry path currently validates protocol, flags and count, but\nit does not validate the range encoding itself. As a result, malformed\nrules can mark the last slot as a range start or place two range starts\nback to back, leaving ports_match_v1() to step past the last valid\nports[] element while interpreting the rule.\n\nReject malformed multiport v1 rules in checkentry by validating that\neach range start has a following element and that the following element\nis not itself marked as another range start.","publishedAt":"2026-04-25T08:46:57.995Z","updatedAt":"2026-10-15T01:17:49.413Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a89ecb6a2ef732d04058d87801e2b6bd7e5c7089","status":"affected","lessThan":"8c5bf8f5b478f569191c4a7982de7cd5f5f73c1a","versionType":"git"},{"version":"a89ecb6a2ef732d04058d87801e2b6bd7e5c7089","status":"affected","lessThan":"c9749f6232c845e31c21d4cc72200211df15d8a2","versionType":"git"},{"version":"a89ecb6a2ef732d04058d87801e2b6bd7e5c7089","status":"affected","lessThan":"b67d638cbee9975c765feb45c126e96ed11ec802","versionType":"git"},{"version":"a89ecb6a2ef732d04058d87801e2b6bd7e5c7089","status":"affected","lessThan":"36bf0d98e180a7c384c8d8a59b0d2d4b80e5eb16","versionType":"git"},{"version":"a89ecb6a2ef732d04058d87801e2b6bd7e5c7089","status":"affected","lessThan":"aec14808271f2bf2b656de6ff12dfe73c5fd3b67","versionType":"git"},{"version":"a89ecb6a2ef732d04058d87801e2b6bd7e5c7089","status":"affected","lessThan":"8368ce8eb01f0b91111d814703696e780d0ef12f","versionType":"git"},{"version":"a89ecb6a2ef732d04058d87801e2b6bd7e5c7089","status":"affected","lessThan":"1e4baa853f1cc4227e04f52d6860524707cfb294","versionType":"git"},{"version":"a89ecb6a2ef732d04058d87801e2b6bd7e5c7089","status":"affected","lessThan":"ff64c5bfef12461df8450e0f50bb693b5269c720","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/xt_multiport.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":"6.6.136","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.83","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.24","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.14","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","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_multiport.c"]}],"references":["https://git.kernel.org/stable/c/8c5bf8f5b478f569191c4a7982de7cd5f5f73c1a","https://git.kernel.org/stable/c/c9749f6232c845e31c21d4cc72200211df15d8a2","https://git.kernel.org/stable/c/b67d638cbee9975c765feb45c126e96ed11ec802","https://git.kernel.org/stable/c/36bf0d98e180a7c384c8d8a59b0d2d4b80e5eb16","https://git.kernel.org/stable/c/aec14808271f2bf2b656de6ff12dfe73c5fd3b67","https://git.kernel.org/stable/c/8368ce8eb01f0b91111d814703696e780d0ef12f","https://git.kernel.org/stable/c/1e4baa853f1cc4227e04f52d6860524707cfb294","https://git.kernel.org/stable/c/ff64c5bfef12461df8450e0f50bb693b5269c720","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html","https://cert-portal.siemens.com/productcert/html/ssa-784472.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31681.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31681","state":"PUBLISHED","datePublished":"2026-04-25T08:46:57.995Z","dateUpdated":"2026-10-15T01:17:49.413Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.130Z"},"containers":{"cna":{"title":"netfilter: xt_multiport: validate range encoding in checkentry","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_multiport: validate range encoding in checkentry\n\nports_match_v1() treats any non-zero pflags entry as the start of a\nport range and unconditionally consumes the next ports[] element as\nthe range end.\n\nThe checkentry path currently validates protocol, flags and count, but\nit does not validate the range encoding itself. 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