CVE-2026-64551 (GCVE-0-2026-64551)
Vulnerability from cvelistv5
Published
2026-07-27 20:10
Modified
2026-08-17 04:57
Severity ?
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: sctp: validate STALE_COOKIE cause length before reading staleness When an ERROR chunk with a STALE_COOKIE cause is received in the COOKIE_ECHOED state, sctp_sf_do_5_2_6_stale() reads the 4-byte Measure of Staleness that follows the cause header: err = (struct sctp_errhdr *)(chunk->skb->data); stale = ntohl(*(__be32 *)((u8 *)err + sizeof(*err))); err is the first cause in the chunk, not the STALE_COOKIE cause that caused the dispatch, and nothing guarantees the staleness field is present. sctp_walk_errors() only requires a cause to be as long as the 4-byte header, so for a STALE_COOKIE cause of length 4 the read runs past the cause, and for a minimal ERROR chunk past skb->tail. The value is echoed to the peer in the Cookie Preservative of the reply INIT, leaking uninitialized memory. sctp_sf_cookie_echoed_err() already walks to the STALE_COOKIE cause, so check its length there and pass it to sctp_sf_do_5_2_6_stale(), which reads that cause instead of the first one. A STALE_COOKIE cause too short to hold the staleness field is discarded. The read is reachable by any peer that can drive an association into COOKIE_ECHOED, including an unprivileged process using a raw SCTP socket in a user and network namespace.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sctp/sm_statefuns.c"
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          "vendor": "Linux",
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              "status": "unaffected",
              "version": "5.15.212",
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              "version": "7.1.5",
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: validate STALE_COOKIE cause length before reading staleness\n\nWhen an ERROR chunk with a STALE_COOKIE cause is received in the\nCOOKIE_ECHOED state, sctp_sf_do_5_2_6_stale() reads the 4-byte Measure\nof Staleness that follows the cause header:\n\n\terr   = (struct sctp_errhdr *)(chunk-\u003eskb-\u003edata);\n\tstale = ntohl(*(__be32 *)((u8 *)err + sizeof(*err)));\n\nerr is the first cause in the chunk, not the STALE_COOKIE cause that\ncaused the dispatch, and nothing guarantees the staleness field is\npresent. sctp_walk_errors() only requires a cause to be as long as the\n4-byte header, so for a STALE_COOKIE cause of length 4 the read runs\npast the cause, and for a minimal ERROR chunk past skb-\u003etail. The value\nis echoed to the peer in the Cookie Preservative of the reply INIT,\nleaking uninitialized memory.\n\nsctp_sf_cookie_echoed_err() already walks to the STALE_COOKIE cause, so\ncheck its length there and pass it to sctp_sf_do_5_2_6_stale(), which\nreads that cause instead of the first one. A STALE_COOKIE cause too\nshort to hold the staleness field is discarded.\n\nThe read is reachable by any peer that can drive an association into\nCOOKIE_ECHOED, including an unprivileged process using a raw SCTP socket\nin a user and network namespace."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable code is in the SCTP receive-side state machine and is driven entirely by an attacker-crafted ERROR chunk arriving over the network; no local access is needed. Per kernel guidance, net/ stack bugs reachable via received packets (SCTP explicitly) are Network.\nAC:L - The attacker fully controls the trigger: acting as the SCTP peer it answers INIT with INIT-ACK to place the association in COOKIE_ECHOED, then sends a minimal ERROR chunk with a 4-byte STALE_COOKIE cause as the last chunk in the packet. There is no race, no memory-layout dependency, and the vtag needed is the one the victim itself advertised in its INIT.\nPR:N - SCTP association setup is unauthenticated; the only check is sctp_vtag_verify() against a tag the peer already received in the victim\u0027s INIT. The attacker needs no credentials or privileges on the target system.\nUI:N - No human user action is required \u2014 SCTP client daemons (SIGTRAN, Diameter, cluster transports) establish and retry associations automatically, and an on-path attacker can inject the ERROR into an in-progress handshake. In the local variant an unprivileged process creates both sides itself with no user involved.\nS:U - The out-of-bounds read and the resulting disclosure stay within the kernel\u0027s own security authority; no VM, sandbox, or IOMMU boundary is crossed.\nC:H - Uninitialized kernel memory past skb-\u003etail is read and then transmitted straight back to the attacker inside the reply INIT\u0027s Cookie Preservative parameter, and the attack can be repeated indefinitely to sample recycled network-buffer memory that may contain remnants of other connections\u0027 traffic. This is a remote, unauthenticated, repeatable kernel heap disclosure oracle, matching the C:H treatment given to the sibling SCTP uninit-read CVE-2026-53225.\nI:N - The bug is a pure read; nothing in kernel memory or in the victim\u0027s association state is modified. The only affected value is a protocol field in a packet sent to the attacker itself.\nA:H - The read runs past the end of the received packet data, a memory-safety violation whose target is not proven to remain inside the skb\u0027s allocation across all receive paths (GSO/frag_list segments, UDP-encapsulated and linearized skbs), so it can fault and oops; kernel guidance and the CNA\u0027s scoring of the equivalent SCTP out-of-bounds-read bug both treat this class as A:H."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:57:28.771Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/6022da37786701df1fc5dd946a6dcba59d5473b1"
        },
        {
          "url": "https://git.kernel.org/stable/c/861f884f5471632c731cbbd612a1c072e391a624"
        },
        {
          "url": "https://git.kernel.org/stable/c/588706ebaf8cdb4a4161602949eba365514b1db1"
        },
        {
          "url": "https://git.kernel.org/stable/c/a257b41ddfe9e327b26581ad2777f04b23ac73f5"
        },
        {
          "url": "https://git.kernel.org/stable/c/08a8f2d13f703924316e9aeac863a88ef50990c7"
        },
        {
          "url": "https://git.kernel.org/stable/c/ebe0a55d954fa8da383b6192edb8f763dcb002d5"
        },
        {
          "url": "https://git.kernel.org/stable/c/bbd6b2ea966cf57b6ae095cf5a8dbc993cd197a0"
        },
        {
          "url": "https://git.kernel.org/stable/c/1cd23ca80784223fa2204e16203f754da4e821f8"
        }
      ],
      "title": "sctp: validate STALE_COOKIE cause length before reading staleness",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64551",
    "datePublished": "2026-07-27T20:10:40.012Z",
    "dateReserved": "2026-07-19T15:36:31.796Z",
    "dateUpdated": "2026-08-17T04:57:28.771Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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