FKIE_CVE-2026-98531

Vulnerability from fkie_nvd - Published: 2026-10-18 16:17 - Updated: 2026-10-19 10:19
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: ipv6: sr: enforce exact attribute length for SEG6_ATTR_DST In seg6_genl_policy, SEG6_ATTR_DST is defined with .type = NLA_BINARY and .len = sizeof(struct in6_addr). For NLA_BINARY, .len only enforces the maximum payload length and permits shorter payloads (e.g., 0 bytes). When seg6_genl_set_tunsrc() copies sizeof(struct in6_addr) bytes via kmemdup(val, sizeof(*val), GFP_KERNEL), a short SEG6_ATTR_DST attribute triggers a 16-byte out-of-bounds read past skb->tail into uninitialized skb->head memory, which is stored in sdata->tun_src and leaked back to userspace via SEG6_CMD_GET_TUNSRC. Switch SEG6_ATTR_DST in seg6_genl_policy to NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)) so that generic netlink validation rejects any attribute whose length is not exactly sizeof(struct in6_addr) with -ERANGE. Tested in QEMU against Linux 7.3.0-rc3 by sending a SEG6_CMD_SET_TUNSRC Generic Netlink message with a 0-byte SEG6_ATTR_DST attribute followed by SEG6_CMD_GET_TUNSRC. On the unfixed kernel, SEG6_CMD_SET_TUNSRC succeeds (err = 0) and SEG6_CMD_GET_TUNSRC leaks 16 bytes of uninitialized kernel heap memory (tun_src = 836a61ecc4d25a1042a8d60411cfb378); with this patch applied, SEG6_CMD_SET_TUNSRC is rejected by netlink policy validation with -ERANGE (-34) and tun_src remains zeroed.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/050a0aa3c80907b8c60a396b7e04d48d8b1a9e70
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/195813bb7324c338eaba0aaa02b18681ee65b670
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/209eefebee54c4a5f01d68b61e8ac9881eca2de9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2d959c75c27f90e9ec489d18ce5ee6b852ad4741
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/66bf65fa109326e4c4ddeb0b94093379f72838fd
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6fcfc362344edea745a69f3a705de50b731f3418
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e3ac68c1cdc2535d127b2bfd50c263d16c8e4199
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/seg6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "050a0aa3c80907b8c60a396b7e04d48d8b1a9e70",
              "status": "affected",
              "version": "915d7e5e5930b4f01d0971d93b9b25ed17d221aa",
              "versionType": "git"
            },
            {
              "lessThan": "209eefebee54c4a5f01d68b61e8ac9881eca2de9",
              "status": "affected",
              "version": "915d7e5e5930b4f01d0971d93b9b25ed17d221aa",
              "versionType": "git"
            },
            {
              "lessThan": "e3ac68c1cdc2535d127b2bfd50c263d16c8e4199",
              "status": "affected",
              "version": "915d7e5e5930b4f01d0971d93b9b25ed17d221aa",
              "versionType": "git"
            },
            {
              "lessThan": "66bf65fa109326e4c4ddeb0b94093379f72838fd",
              "status": "affected",
              "version": "915d7e5e5930b4f01d0971d93b9b25ed17d221aa",
              "versionType": "git"
            },
            {
              "lessThan": "195813bb7324c338eaba0aaa02b18681ee65b670",
              "status": "affected",
              "version": "915d7e5e5930b4f01d0971d93b9b25ed17d221aa",
              "versionType": "git"
            },
            {
              "lessThan": "6fcfc362344edea745a69f3a705de50b731f3418",
              "status": "affected",
              "version": "915d7e5e5930b4f01d0971d93b9b25ed17d221aa",
              "versionType": "git"
            },
            {
              "lessThan": "94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e",
              "status": "affected",
              "version": "915d7e5e5930b4f01d0971d93b9b25ed17d221aa",
              "versionType": "git"
            },
            {
              "lessThan": "2d959c75c27f90e9ec489d18ce5ee6b852ad4741",
              "status": "affected",
              "version": "915d7e5e5930b4f01d0971d93b9b25ed17d221aa",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/seg6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.10"
            },
            {
              "lessThan": "4.10",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.271",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.222",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "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-\u003etail into uninitialized\nskb-\u003ehead memory, which is stored in sdata-\u003etun_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."
    }
  ],
  "id": "CVE-2026-98531",
  "lastModified": "2026-10-19T10:19:08.527",
  "metrics": {},
  "published": "2026-10-18T16:17:04.653",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/050a0aa3c80907b8c60a396b7e04d48d8b1a9e70"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/195813bb7324c338eaba0aaa02b18681ee65b670"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/209eefebee54c4a5f01d68b61e8ac9881eca2de9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/2d959c75c27f90e9ec489d18ce5ee6b852ad4741"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/66bf65fa109326e4c4ddeb0b94093379f72838fd"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6fcfc362344edea745a69f3a705de50b731f3418"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e3ac68c1cdc2535d127b2bfd50c263d16c8e4199"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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