CVE-2026-63971 (GCVE-0-2026-63971)
Vulnerability from cvelistv5
Published
2026-07-19 14:55
Modified
2026-08-05 12:37
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: sctp: fix race between sctp_wait_for_connect and peeloff sctp_wait_for_connect() drops and re-acquires the socket lock while waiting for the association to reach ESTABLISHED state. During this window, another thread can peeloff the association to a new socket via getsockopt(SCTP_SOCKOPT_PEELOFF), changing asoc->base.sk. After re-acquiring the old socket lock, sctp_wait_for_connect() returns success without noticing the migration — the caller then accesses the association under the wrong lock in sctp_datamsg_from_user(). Add the same sk != asoc->base.sk check that sctp_wait_for_sndbuf() already has, returning an error if the association was migrated while we slept.
References
Impacted products
Vendor Product Version
Linux Linux Version: 668c9beb9020d5834ee9e43c208190a07d2b1928
Version: 668c9beb9020d5834ee9e43c208190a07d2b1928
Version: 668c9beb9020d5834ee9e43c208190a07d2b1928
Version: 668c9beb9020d5834ee9e43c208190a07d2b1928
Version: 668c9beb9020d5834ee9e43c208190a07d2b1928
Version: 668c9beb9020d5834ee9e43c208190a07d2b1928
Version: 668c9beb9020d5834ee9e43c208190a07d2b1928
Version: 668c9beb9020d5834ee9e43c208190a07d2b1928
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sctp/socket.c"
          ],
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          "vendor": "Linux",
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "4.16"
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              "version": "0",
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              "version": "5.10.259",
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              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.6.143",
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              "status": "unaffected",
              "version": "6.12.93",
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              "status": "unaffected",
              "version": "6.18.35",
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              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.259",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
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                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: fix race between sctp_wait_for_connect and peeloff\n\nsctp_wait_for_connect() drops and re-acquires the socket lock while\nwaiting for the association to reach ESTABLISHED state. During this\nwindow, another thread can peeloff the association to a new socket via\ngetsockopt(SCTP_SOCKOPT_PEELOFF), changing asoc-\u003ebase.sk. After\nre-acquiring the old socket lock, sctp_wait_for_connect() returns\nsuccess without noticing the migration \u2014 the caller then accesses\nthe association under the wrong lock in sctp_datamsg_from_user().\n\nAdd the same sk != asoc-\u003ebase.sk check that sctp_wait_for_sndbuf()\nalready has, returning an error if the association was migrated while\nwe slept."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Exploitation requires local syscalls on an SCTP socket (`sendmsg`/`sendto` to trigger `sctp_wait_for_connect`, and `getsockopt(SCTP_SOCKOPT_PEELOFF)` to peel off the association). A remote peer can only help complete the SCTP handshake; it cannot invoke peeloff or the racing send path.\nAC:L - The attacker controls both sides of the race by running concurrent threads on the same SCTP one-to-many socket, timing peeloff during the window where `sctp_wait_for_connect()` has released the socket lock. Required options (`SCTP_FRAGMENT_INTERLEAVE`, `SCTP_INTERLEAVING_SUPPORTED`, and `net.sctp.intl_enable`) are attacker-settable in a user/net namespace.\nPR:L - No real-root capability is required; an unprivileged user can create SCTP sockets and drive the full race from a user namespace (`unshare -Urn`), including enabling `net.sctp.intl_enable` and the interleaving socket options needed to reach the vulnerable `sctp_sendmsg_to_asoc()` path.\nUI:N - Exploitation is fully attacker-driven through coordinated local threads and does not require any action from a victim user or administrator beyond normal SCTP socket use.\nS:U - Impact is confined to kernel memory integrity/availability within the same security authority; successful exploitation would be local privilege escalation, not a cross-boundary escape such as VM or container breakout by itself.\nC:H - After peeloff migrates `asoc-\u003ebase.sk`, the caller continues in `sctp_datamsg_from_user()` while holding the wrong socket lock, creating unsynchronized concurrent access to association/stream state that can corrupt kernel heap metadata and be leveraged for arbitrary kernel memory disclosure.\nI:H - The post-race path builds and queues DATA/I-DATA chunks via `sctp_datamsg_from_user()` and `sctp_primitive_SEND()` without the correct socket lock, enabling concurrent modification of association output queues and stream structures that can be turned into arbitrary kernel writes or control-flow hijacking.\nA:H - Concurrent unsynchronized access to a live SCTP association after peeloff can cause kernel oops/panic or wedged associations, and the underlying race is a classic kernel concurrency defect with high availability impact even before full exploitation."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:37:42.789Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0e0d5bc76fd4267a71334fcc8f1a5fbcf997845d"
        },
        {
          "url": "https://git.kernel.org/stable/c/bcfeac79af740735ace44008b4a11b8e5add20f5"
        },
        {
          "url": "https://git.kernel.org/stable/c/8e9b56051d24540cfbf39194618708c4a7633549"
        },
        {
          "url": "https://git.kernel.org/stable/c/634a9af8a26a84d8b0d7b3b643204b344b42d9fb"
        },
        {
          "url": "https://git.kernel.org/stable/c/7d2038d4b80166f7bead8d07eba3b97405816c21"
        },
        {
          "url": "https://git.kernel.org/stable/c/68667ee4c7dadf7f63167234e2a1af09b3f7874e"
        },
        {
          "url": "https://git.kernel.org/stable/c/6140cfa721451fa6e18e134e709703c2bf34d0fb"
        },
        {
          "url": "https://git.kernel.org/stable/c/f14fe6395a8b3d961a61e138ad7b36ba3626dd4e"
        }
      ],
      "title": "sctp: fix race between sctp_wait_for_connect and peeloff",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63971",
    "datePublished": "2026-07-19T14:55:57.792Z",
    "dateReserved": "2026-07-19T07:54:57.024Z",
    "dateUpdated": "2026-08-05T12:37:42.789Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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