{"id":"CVE-2026-98531","state":"PUBLISHED","title":"ipv6: sr: enforce exact attribute length for SEG6_ATTR_DST","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: sr: enforce exact attribute length for SEG6_ATTR_DST\n\nIn seg6_genl_policy, SEG6_ATTR_DST is defined with .type = NLA_BINARY and\n.len = sizeof(struct in6_addr). For NLA_BINARY, .len only enforces the\nmaximum payload length and permits shorter payloads (e.g., 0 bytes).\nWhen seg6_genl_set_tunsrc() copies sizeof(struct in6_addr) bytes via\nkmemdup(val, sizeof(*val), GFP_KERNEL), a short SEG6_ATTR_DST attribute\ntriggers a 16-byte out-of-bounds read past skb->tail into uninitialized\nskb->head memory, which is stored in sdata->tun_src and leaked back to\nuserspace via SEG6_CMD_GET_TUNSRC.\n\nSwitch SEG6_ATTR_DST in seg6_genl_policy to\nNLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)) so that generic netlink\nvalidation rejects any attribute whose length is not exactly\nsizeof(struct in6_addr) with -ERANGE.\n\nTested in QEMU against Linux 7.3.0-rc3 by sending a SEG6_CMD_SET_TUNSRC\nGeneric Netlink message with a 0-byte SEG6_ATTR_DST attribute followed\nby SEG6_CMD_GET_TUNSRC. On the unfixed kernel, SEG6_CMD_SET_TUNSRC\nsucceeds (err = 0) and SEG6_CMD_GET_TUNSRC leaks 16 bytes of\nuninitialized kernel heap memory (tun_src =\n836a61ecc4d25a1042a8d60411cfb378); with this patch applied,\nSEG6_CMD_SET_TUNSRC is rejected by netlink policy validation with\n-ERANGE (-34) and tun_src remains zeroed.","publishedAt":"2026-10-18T15:17:49.632Z","updatedAt":"2026-10-19T09:21:14.351Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"050a0aa3c80907b8c60a396b7e04d48d8b1a9e70","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"209eefebee54c4a5f01d68b61e8ac9881eca2de9","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"e3ac68c1cdc2535d127b2bfd50c263d16c8e4199","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"66bf65fa109326e4c4ddeb0b94093379f72838fd","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"195813bb7324c338eaba0aaa02b18681ee65b670","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"6fcfc362344edea745a69f3a705de50b731f3418","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"2d959c75c27f90e9ec489d18ce5ee6b852ad4741","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/seg6.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.10","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.55","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.9","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/seg6.c"]}],"references":["https://git.kernel.org/stable/c/050a0aa3c80907b8c60a396b7e04d48d8b1a9e70","https://git.kernel.org/stable/c/209eefebee54c4a5f01d68b61e8ac9881eca2de9","https://git.kernel.org/stable/c/e3ac68c1cdc2535d127b2bfd50c263d16c8e4199","https://git.kernel.org/stable/c/66bf65fa109326e4c4ddeb0b94093379f72838fd","https://git.kernel.org/stable/c/195813bb7324c338eaba0aaa02b18681ee65b670","https://git.kernel.org/stable/c/6fcfc362344edea745a69f3a705de50b731f3418","https://git.kernel.org/stable/c/94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e","https://git.kernel.org/stable/c/2d959c75c27f90e9ec489d18ce5ee6b852ad4741"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98531.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98531","state":"PUBLISHED","datePublished":"2026-10-18T15:17:49.632Z","dateUpdated":"2026-10-19T09:21:14.351Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.355Z"},"containers":{"cna":{"title":"ipv6: sr: enforce exact attribute length for SEG6_ATTR_DST","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: sr: enforce exact attribute length for SEG6_ATTR_DST\n\nIn seg6_genl_policy, SEG6_ATTR_DST is defined with .type = NLA_BINARY and\n.len = sizeof(struct in6_addr). For NLA_BINARY, .len only enforces the\nmaximum payload length and permits shorter payloads (e.g., 0 bytes).\nWhen seg6_genl_set_tunsrc() copies sizeof(struct in6_addr) bytes via\nkmemdup(val, sizeof(*val), GFP_KERNEL), a short SEG6_ATTR_DST attribute\ntriggers a 16-byte out-of-bounds read past skb->tail into uninitialized\nskb->head memory, which is stored in sdata->tun_src and leaked back to\nuserspace via SEG6_CMD_GET_TUNSRC.\n\nSwitch SEG6_ATTR_DST in seg6_genl_policy to\nNLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)) so that generic netlink\nvalidation rejects any attribute whose length is not exactly\nsizeof(struct in6_addr) with -ERANGE.\n\nTested in QEMU against Linux 7.3.0-rc3 by sending a SEG6_CMD_SET_TUNSRC\nGeneric Netlink message with a 0-byte SEG6_ATTR_DST attribute followed\nby SEG6_CMD_GET_TUNSRC. On the unfixed kernel, SEG6_CMD_SET_TUNSRC\nsucceeds (err = 0) and SEG6_CMD_GET_TUNSRC leaks 16 bytes of\nuninitialized kernel heap memory (tun_src =\n836a61ecc4d25a1042a8d60411cfb378); with this patch applied,\nSEG6_CMD_SET_TUNSRC is rejected by netlink policy validation with\n-ERANGE (-34) and tun_src remains zeroed."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"050a0aa3c80907b8c60a396b7e04d48d8b1a9e70","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"209eefebee54c4a5f01d68b61e8ac9881eca2de9","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"e3ac68c1cdc2535d127b2bfd50c263d16c8e4199","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"66bf65fa109326e4c4ddeb0b94093379f72838fd","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"195813bb7324c338eaba0aaa02b18681ee65b670","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"6fcfc362344edea745a69f3a705de50b731f3418","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e","versionType":"git"},{"version":"915d7e5e5930b4f01d0971d93b9b25ed17d221aa","status":"affected","lessThan":"2d959c75c27f90e9ec489d18ce5ee6b852ad4741","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/seg6.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.10","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.55","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.9","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/seg6.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/050a0aa3c80907b8c60a396b7e04d48d8b1a9e70"},{"url":"https://git.kernel.org/stable/c/209eefebee54c4a5f01d68b61e8ac9881eca2de9"},{"url":"https://git.kernel.org/stable/c/e3ac68c1cdc2535d127b2bfd50c263d16c8e4199"},{"url":"https://git.kernel.org/stable/c/66bf65fa109326e4c4ddeb0b94093379f72838fd"},{"url":"https://git.kernel.org/stable/c/195813bb7324c338eaba0aaa02b18681ee65b670"},{"url":"https://git.kernel.org/stable/c/6fcfc362344edea745a69f3a705de50b731f3418"},{"url":"https://git.kernel.org/stable/c/94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e"},{"url":"https://git.kernel.org/stable/c/2d959c75c27f90e9ec489d18ce5ee6b852ad4741"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:21:14.351Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"5.10.271"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.12.112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"6.18.55"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"7.2.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}