{"id":"CVE-2026-98531","published":"2026-10-18T16:17:04.653","lastModified":"2026-10-19T10:19:08.527","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.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/050a0aa3c80907b8c60a396b7e04d48d8b1a9e70","tags":[]},{"url":"https://git.kernel.org/stable/c/195813bb7324c338eaba0aaa02b18681ee65b670","tags":[]},{"url":"https://git.kernel.org/stable/c/209eefebee54c4a5f01d68b61e8ac9881eca2de9","tags":[]},{"url":"https://git.kernel.org/stable/c/2d959c75c27f90e9ec489d18ce5ee6b852ad4741","tags":[]},{"url":"https://git.kernel.org/stable/c/66bf65fa109326e4c4ddeb0b94093379f72838fd","tags":[]},{"url":"https://git.kernel.org/stable/c/6fcfc362344edea745a69f3a705de50b731f3418","tags":[]},{"url":"https://git.kernel.org/stable/c/94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e","tags":[]},{"url":"https://git.kernel.org/stable/c/e3ac68c1cdc2535d127b2bfd50c263d16c8e4199","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}