CVE-2026-98525 (GCVE-0-2026-98525)
Vulnerability from cvelistv5
Published
2026-10-18 15:17
Modified
2026-10-19 09:21
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mctp: route: iterate socket tag list in mctp_lookup_prealloc_tag() When a socket transmits a packet with MCTP_TAG_PREALLOC set, mctp_lookup_prealloc_tag() iterates over the per-netns &mns->keys list and matches netid, req_tag, peer_addr, and manual_alloc, without checking whether tmp->sk == &msk->sk. This allows any MCTP socket in the same network namespace to use and consume another socket's preallocated tag. Iterate the socket's own tag list (&msk->keys via sklist) instead of the namespace-wide &mns->keys list in mctp_lookup_prealloc_tag(), ensuring that only tags allocated by msk are matched. Tested in QEMU against Linux 7.3.0-rc3 by allocating a manual tag (0x18) on socket A via SIOCMCTPALLOCTAG for peer EID 9 and sending a 4-byte message with MCTP_TAG_PREALLOC from socket B in the same network namespace. On the unfixed kernel, sendto(sock_b) using socket A's preallocated tag succeeds (ret = 4); with this patch applied, sendto(sock_b) fails with -ENOENT (errno = 2) while sendto(sock_a) succeeds (ret = 4).
References
Impacted products
Vendor Product Version
Linux Linux Version: 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa
Version: 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa
Version: 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa
Version: 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mctp/route.c"
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          "vendor": "Linux",
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              "versionType": "semver"
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              "version": "6.12.112",
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              "status": "unaffected",
              "version": "6.18.55",
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              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
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                  "versionEndExcluding": "6.12.112",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "negate": false,
              "operator": "OR"
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          ]
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmctp: route: iterate socket tag list in mctp_lookup_prealloc_tag()\n\nWhen a socket transmits a packet with MCTP_TAG_PREALLOC set,\nmctp_lookup_prealloc_tag() iterates over the per-netns \u0026mns-\u003ekeys list\nand matches netid, req_tag, peer_addr, and manual_alloc, without\nchecking whether tmp-\u003esk == \u0026msk-\u003esk. This allows any MCTP socket in the\nsame network namespace to use and consume another socket\u0027s preallocated\ntag.\n\nIterate the socket\u0027s own tag list (\u0026msk-\u003ekeys via sklist) instead of the\nnamespace-wide \u0026mns-\u003ekeys list in mctp_lookup_prealloc_tag(), ensuring\nthat only tags allocated by msk are matched.\n\nTested in QEMU against Linux 7.3.0-rc3 by allocating a manual tag\n(0x18) on socket A via SIOCMCTPALLOCTAG for peer EID 9 and sending a\n4-byte message with MCTP_TAG_PREALLOC from socket B in the same network\nnamespace. On the unfixed kernel, sendto(sock_b) using socket A\u0027s\npreallocated tag succeeds (ret = 4); with this patch applied,\nsendto(sock_b) fails with -ENOENT (errno = 2) while sendto(sock_a)\nsucceeds (ret = 4)."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:21:07.010Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/09299addab11857e92eca55cd8ef3350b927c90c"
        },
        {
          "url": "https://git.kernel.org/stable/c/e35cb500dd14882f8dee61783fccd1823fd3ab0d"
        },
        {
          "url": "https://git.kernel.org/stable/c/f178300e2f56ca9ec2a3a0090608730bbee0af7b"
        },
        {
          "url": "https://git.kernel.org/stable/c/26cc0e69cce062cd3aa6fae33074684669c35a71"
        }
      ],
      "title": "mctp: route: iterate socket tag list in mctp_lookup_prealloc_tag()",
      "x_generator": {
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  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98525",
    "datePublished": "2026-10-18T15:17:43.216Z",
    "dateReserved": "2026-09-25T10:25:14.355Z",
    "dateUpdated": "2026-10-19T09:21:07.010Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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