CVE-2026-43186 (GCVE-0-2026-43186)
Vulnerability from cvelistv5
Published
2026-05-06 11:27
Modified
2026-08-05 12:26
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data() On the receive path, __ioam6_fill_trace_data() uses trace->nodelen to decide how much data to write for each node. It trusts this field as-is from the incoming packet, with no consistency check against trace->type (the 24-bit field that tells which data items are present). A crafted packet can set nodelen=0 while setting type bits 0-21, causing the function to write ~100 bytes past the allocated region (into skb_shared_info), which corrupts adjacent heap memory and leads to a kernel panic. Add a shared helper ioam6_trace_compute_nodelen() in ioam6.c to derive the expected nodelen from the type field, and use it: - in ioam6_iptunnel.c (send path, existing validation) to replace the open-coded computation; - in exthdrs.c (receive path, ipv6_hop_ioam) to drop packets whose nodelen is inconsistent with the type field, before any data is written. Per RFC 9197, bits 12-21 are each short (4-octet) fields, so they are included in IOAM6_MASK_SHORT_FIELDS (changed from 0xff100000 to 0xff1ffc00).
References
Impacted products
Vendor Product Version
Linux Linux Version: 9ee11f0fff205b4b3df9750bff5e94f97c71b6a0
Version: 9ee11f0fff205b4b3df9750bff5e94f97c71b6a0
Version: 9ee11f0fff205b4b3df9750bff5e94f97c71b6a0
Version: 9ee11f0fff205b4b3df9750bff5e94f97c71b6a0
Version: 9ee11f0fff205b4b3df9750bff5e94f97c71b6a0
Version: 9ee11f0fff205b4b3df9750bff5e94f97c71b6a0
Version: 9ee11f0fff205b4b3df9750bff5e94f97c71b6a0
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/ioam6.h",
            "net/ipv6/exthdrs.c",
            "net/ipv6/ioam6.c",
            "net/ipv6/ioam6_iptunnel.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f4d9d4b8fd839719d564651671e24c62c545c23b",
              "status": "affected",
              "version": "9ee11f0fff205b4b3df9750bff5e94f97c71b6a0",
              "versionType": "git"
            },
            {
              "lessThan": "fb3c662fafebc5b9d74417ed1de8759f6bb72143",
              "status": "affected",
              "version": "9ee11f0fff205b4b3df9750bff5e94f97c71b6a0",
              "versionType": "git"
            },
            {
              "lessThan": "632d233cf2e64a46865ae2c064ae3c9df7c8864f",
              "status": "affected",
              "version": "9ee11f0fff205b4b3df9750bff5e94f97c71b6a0",
              "versionType": "git"
            },
            {
              "lessThan": "0591d6509c2ff13f09ea2998434aba0c0472e978",
              "status": "affected",
              "version": "9ee11f0fff205b4b3df9750bff5e94f97c71b6a0",
              "versionType": "git"
            },
            {
              "lessThan": "e90346a2f1e8917d5760a44a1f61c44e3b36d96b",
              "status": "affected",
              "version": "9ee11f0fff205b4b3df9750bff5e94f97c71b6a0",
              "versionType": "git"
            },
            {
              "lessThan": "ea3632aefc04205436868541638e26f4a74d5637",
              "status": "affected",
              "version": "9ee11f0fff205b4b3df9750bff5e94f97c71b6a0",
              "versionType": "git"
            },
            {
              "lessThan": "6db8b56eed62baacaf37486e83378a72635c04cc",
              "status": "affected",
              "version": "9ee11f0fff205b4b3df9750bff5e94f97c71b6a0",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/net/ioam6.h",
            "net/ipv6/exthdrs.c",
            "net/ipv6/ioam6.c",
            "net/ipv6/ioam6_iptunnel.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.202",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.165",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.128",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.75",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.16",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.202",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.165",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.128",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.75",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.16",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.6",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()\n\nOn the receive path, __ioam6_fill_trace_data() uses trace-\u003enodelen\nto decide how much data to write for each node. It trusts this field\nas-is from the incoming packet, with no consistency check against\ntrace-\u003etype (the 24-bit field that tells which data items are\npresent). A crafted packet can set nodelen=0 while setting type bits\n0-21, causing the function to write ~100 bytes past the allocated\nregion (into skb_shared_info), which corrupts adjacent heap memory\nand leads to a kernel panic.\n\nAdd a shared helper ioam6_trace_compute_nodelen() in ioam6.c to\nderive the expected nodelen from the type field, and use it:\n\n  - in ioam6_iptunnel.c (send path, existing validation) to replace\n    the open-coded computation;\n  - in exthdrs.c (receive path, ipv6_hop_ioam) to drop packets whose\n    nodelen is inconsistent with the type field, before any data is\n    written.\n\nPer RFC 9197, bits 12-21 are each short (4-octet) fields, so they\nare included in IOAM6_MASK_SHORT_FIELDS (changed from 0xff100000 to\n0xff1ffc00)."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable code is reached while processing received IPv6 Hop-by-Hop IOAM options in the network stack. A remote packet sender can craft the IOAM trace header for an IOAM-enabled target.\nAC:L - Exploitation requires a malformed but straightforward IOAM Pre-allocated Trace option with inconsistent nodelen and type fields. There is no race or attacker-uncontrolled timing condition once IOAM is enabled on the target interface.\nPR:N - The packet processing path has no authentication or per-sender privilege check before calling the vulnerable fill routine. Although enabling IOAM and creating namespaces is administrative setup, a remote attacker against such a deployment needs no privileges.\nUI:N - No victim user action is needed. The vulnerable path runs automatically when the kernel receives and parses the crafted IPv6 packet.\nS:U - The corruption occurs inside the same kernel security authority that processes the packet. This is not a VM escape or other cross-scope boundary bypass.\nC:H - The bug is a kernel heap out-of-bounds write into adjacent skb memory, including skb_shared_info in the described case. Such memory corruption can be leveraged for kernel memory disclosure as part of exploitation.\nI:H - This is an out-of-bounds kernel heap write controlled by attacker-supplied packet fields and layout choices. Kernel heap corruption is defensibly exploitable for arbitrary modification or code execution.\nA:H - The fix commit states the corruption leads to a kernel panic, and malformed packets can be sent repeatedly. Kernel panic or crash is high availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:26:24.342Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f4d9d4b8fd839719d564651671e24c62c545c23b"
        },
        {
          "url": "https://git.kernel.org/stable/c/fb3c662fafebc5b9d74417ed1de8759f6bb72143"
        },
        {
          "url": "https://git.kernel.org/stable/c/632d233cf2e64a46865ae2c064ae3c9df7c8864f"
        },
        {
          "url": "https://git.kernel.org/stable/c/0591d6509c2ff13f09ea2998434aba0c0472e978"
        },
        {
          "url": "https://git.kernel.org/stable/c/e90346a2f1e8917d5760a44a1f61c44e3b36d96b"
        },
        {
          "url": "https://git.kernel.org/stable/c/ea3632aefc04205436868541638e26f4a74d5637"
        },
        {
          "url": "https://git.kernel.org/stable/c/6db8b56eed62baacaf37486e83378a72635c04cc"
        }
      ],
      "title": "ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43186",
    "datePublished": "2026-05-06T11:27:57.053Z",
    "dateReserved": "2026-05-01T14:12:55.991Z",
    "dateUpdated": "2026-08-05T12:26:24.342Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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