CVE-2026-98525 (GCVE-0-2026-98525)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:17 – Updated: 2026-10-19 09:21
VLAI
Title
mctp: route: iterate socket tag list in mctp_lookup_prealloc_tag()
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).
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7018 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa , < 09299addab11857e92eca55cd8ef3350b927c90c (git)
Affected: 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa , < e35cb500dd14882f8dee61783fccd1823fd3ab0d (git)
Affected: 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa , < f178300e2f56ca9ec2a3a0090608730bbee0af7b (git)
Affected: 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa , < 26cc0e69cce062cd3aa6fae33074684669c35a71 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.18
Unaffected: 0 , < 5.18 (semver)
Unaffected: 6.12.112 , ≤ 6.12.* (semver)
Unaffected: 6.18.55 , ≤ 6.18.* (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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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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          "vendor": "Linux",
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              "versionType": "semver"
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      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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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"
      },
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          "url": "https://git.kernel.org/stable/c/09299addab11857e92eca55cd8ef3350b927c90c"
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          "url": "https://git.kernel.org/stable/c/e35cb500dd14882f8dee61783fccd1823fd3ab0d"
        },
        {
          "url": "https://git.kernel.org/stable/c/f178300e2f56ca9ec2a3a0090608730bbee0af7b"
        },
        {
          "url": "https://git.kernel.org/stable/c/26cc0e69cce062cd3aa6fae33074684669c35a71"
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      ],
      "title": "mctp: route: iterate socket tag list in mctp_lookup_prealloc_tag()",
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    "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",
  "vulnerability-lookup:meta": {
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      "date": "2026-11-01",
      "epss": "0.00209",
      "percentile": "0.1109"
    },
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      "cve": "CVE-2026-98525",
      "id": "msrc_CVE-2026-98525",
      "initial_release_date": "2026-10-20T01:02:22.000Z",
      "product_status:known_not_affected": "1",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "mctp: route: iterate socket tag list in mctp_lookup_prealloc_tag()",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98525.json",
      "version": "4"
    },
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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)."
          }
        ],
        "id": "CVE-2026-98525",
        "lastModified": "2026-10-19T10:19:07.707",
        "metrics": {},
        "published": "2026-10-18T16:17:03.953",
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        "vulnStatus": "Received"
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      "current_release_date": "2026-10-19T17:38:47+00:00",
      "cve": "CVE-2026-98525",
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      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_not_affected": "277",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: mctp: route: iterate socket tag list in mctp_lookup_prealloc_tag()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98525.json",
      "version": "3"
    }
  }
}



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