CVE-2026-99165 (GCVE-0-2026-99165)

Vulnerability from cvelistv5 – Published: 2026-10-28 10:35 – Updated: 2026-10-28 10:35
VLAI
Title
sctp: revalidate output stream after association connect wait
Summary
In the Linux kernel, the following vulnerability has been resolved: sctp: revalidate output stream after association connect wait When message interleaving is enabled, the first send waits for association establishment before building its data chunks. The wait drops the socket lock, and handshake processing can reduce the output stream count to the peer-advertised inbound stream count. sctp_stream_init() then frees the extension of every removed stream. The sender resumes with the stream that it checked before the wait. If the peer removed that stream, sctp_outq_tail() later dereferences its NULL extension. Fatal-oops policies then panic the host. KASAN: null-ptr-deref in range [0x38-0x3f] RIP: sctp_outq_tail+0x49e/0xaa0 Call Trace: sctp_primitive_SEND sctp_sendmsg_to_asoc sctp_sendmsg A range check alone is insufficient. Stream reconfiguration can grow the output count again while the lock is released without recreating extensions freed by the earlier shrink. The stream can then be in range while its extension remains NULL. The send-buffer wait has the same issue. Factor the range and extension checks into a helper and repeat both after each send-path wait that drops the socket lock. Once the lock is reacquired, the validation remains stable through data creation and queueing. If validation fails after the connect wait, the auto-created association is already established. Return ESRCH so the existing caller path keeps it under state-machine ownership instead of freeing it directly, which would leave protocol, counter and socket state inconsistent.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 668c9beb9020d5834ee9e43c208190a07d2b1928 , < 77a63d1b813b08c4e5a948f5e04fbaca6176aa8f (git)
Affected: 668c9beb9020d5834ee9e43c208190a07d2b1928 , < fd56ac95ec31a05b66e8938debfa847f49c0e993 (git)
Affected: 668c9beb9020d5834ee9e43c208190a07d2b1928 , < b7ad72414c673ce1fa1f463e807cd4f34f8be9bf (git)
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Linux Linux Affected: 4.16
Unaffected: 0 , < 4.16 (semver)
Unaffected: 6.18.59 , ≤ 6.18.* (semver)
Unaffected: 7.2.13 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sctp/socket.c"
          ],
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          "vendor": "Linux",
          "versions": [
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              "status": "affected",
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          "versions": [
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              "version": "4.16"
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              "versionType": "semver"
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: revalidate output stream after association connect wait\n\nWhen message interleaving is enabled, the first send waits for association\nestablishment before building its data chunks.  The wait drops the socket\nlock, and handshake processing can reduce the output stream count to the\npeer-advertised inbound stream count.  sctp_stream_init() then frees the\nextension of every removed stream.\n\nThe sender resumes with the stream that it checked before the wait.  If the\npeer removed that stream, sctp_outq_tail() later dereferences its NULL\nextension.  Fatal-oops policies then panic the host.\n\nKASAN: null-ptr-deref in range [0x38-0x3f]\nRIP: sctp_outq_tail+0x49e/0xaa0\nCall Trace:\n sctp_primitive_SEND\n sctp_sendmsg_to_asoc\n sctp_sendmsg\n\nA range check alone is insufficient.  Stream reconfiguration can grow the\noutput count again while the lock is released without recreating extensions\nfreed by the earlier shrink.  The stream can then be in range while its\nextension remains NULL.  The send-buffer wait has the same issue.\n\nFactor the range and extension checks into a helper and repeat both after\neach send-path wait that drops the socket lock.  Once the lock is\nreacquired, the validation remains stable through data creation and\nqueueing.\n\nIf validation fails after the connect wait, the auto-created association is\nalready established.  Return ESRCH so the existing caller path keeps it\nunder state-machine ownership instead of freeing it directly, which would\nleave protocol, counter and socket state inconsistent."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:35:17.366Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
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      "title": "sctp: revalidate output stream after association connect wait",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99165",
    "datePublished": "2026-10-28T10:35:17.366Z",
    "dateReserved": "2026-09-25T10:25:14.398Z",
    "dateUpdated": "2026-10-28T10:35:17.366Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "cve": "CVE-2026-99165",
      "date": "2026-10-29",
      "epss": "0.00172",
      "percentile": "0.0662"
    },
    "microsoft_vex": {
      "current_release_date": "2026-10-29T01:06:47.000Z",
      "cve": "CVE-2026-99165",
      "id": "msrc_CVE-2026-99165",
      "initial_release_date": "2026-10-29T01:06:47.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "sctp: revalidate output stream after association connect wait",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-99165.json",
      "version": "1"
    },
    "nvd": {
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              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: revalidate output stream after association connect wait\n\nWhen message interleaving is enabled, the first send waits for association\nestablishment before building its data chunks.  The wait drops the socket\nlock, and handshake processing can reduce the output stream count to the\npeer-advertised inbound stream count.  sctp_stream_init() then frees the\nextension of every removed stream.\n\nThe sender resumes with the stream that it checked before the wait.  If the\npeer removed that stream, sctp_outq_tail() later dereferences its NULL\nextension.  Fatal-oops policies then panic the host.\n\nKASAN: null-ptr-deref in range [0x38-0x3f]\nRIP: sctp_outq_tail+0x49e/0xaa0\nCall Trace:\n sctp_primitive_SEND\n sctp_sendmsg_to_asoc\n sctp_sendmsg\n\nA range check alone is insufficient.  Stream reconfiguration can grow the\noutput count again while the lock is released without recreating extensions\nfreed by the earlier shrink.  The stream can then be in range while its\nextension remains NULL.  The send-buffer wait has the same issue.\n\nFactor the range and extension checks into a helper and repeat both after\neach send-path wait that drops the socket lock.  Once the lock is\nreacquired, the validation remains stable through data creation and\nqueueing.\n\nIf validation fails after the connect wait, the auto-created association is\nalready established.  Return ESRCH so the existing caller path keeps it\nunder state-machine ownership instead of freeing it directly, which would\nleave protocol, counter and socket state inconsistent."
          }
        ],
        "id": "CVE-2026-99165",
        "lastModified": "2026-10-28T11:17:36.917",
        "metrics": {},
        "published": "2026-10-28T11:17:36.917",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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