FKIE_CVE-2026-74696

Vulnerability from fkie_nvd - Published: 2026-08-22 16:16 - Updated: 2026-10-14 13:10
Severity
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: tcp: fix TFO max_qlen accounting across reuseport migration A listener's TCP_FASTOPEN max_qlen stops being accurate and lets through far more pending Fast Open requests than it was configured for. This only shows up with SO_REUSEPORT listener migration, where closing a listener hands its still-pending TFO children over to a surviving one. fastopenq.qlen is charged in tcp_fastopen_create_child() when the child is created and uncharged in reqsk_fastopen_remove() when the handshake completes. The uncharge follows rsk_listener of the request the child points at, and inet_reqsk_clone() has repointed the child at a new request owned by the new listener, so the ++ and the -- land on two different sockets. The new listener's qlen drifts negative and its limit no longer binds. Charge the new listener during migration, like reqsk_queue_migrated() already does for queue->young and queue->qlen.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/585fc5247d14939a561056aa2addd9b7c2b1f670
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6e10ee56524a26b250229ad348637825646ddb88
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a0ab2ba83e35159d81cec830a92e885ecf8139be
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a66e869cf0c90c1e47ae75f72b6482acbfc808ff
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b6247e0f96bd825ffb2005257f6177b5e642dee6
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d974618b2097453778389d385e3741629c40e0a3
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e98f0d80b9cccb5f828425d2004f9686e7d1ae24
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/inet_connection_sock.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e98f0d80b9cccb5f828425d2004f9686e7d1ae24",
              "status": "affected",
              "version": "54b92e84193749c9968aff2dd46e3b0f42643e18",
              "versionType": "git"
            },
            {
              "lessThan": "b6247e0f96bd825ffb2005257f6177b5e642dee6",
              "status": "affected",
              "version": "54b92e84193749c9968aff2dd46e3b0f42643e18",
              "versionType": "git"
            },
            {
              "lessThan": "585fc5247d14939a561056aa2addd9b7c2b1f670",
              "status": "affected",
              "version": "54b92e84193749c9968aff2dd46e3b0f42643e18",
              "versionType": "git"
            },
            {
              "lessThan": "6e10ee56524a26b250229ad348637825646ddb88",
              "status": "affected",
              "version": "54b92e84193749c9968aff2dd46e3b0f42643e18",
              "versionType": "git"
            },
            {
              "lessThan": "a66e869cf0c90c1e47ae75f72b6482acbfc808ff",
              "status": "affected",
              "version": "54b92e84193749c9968aff2dd46e3b0f42643e18",
              "versionType": "git"
            },
            {
              "lessThan": "d974618b2097453778389d385e3741629c40e0a3",
              "status": "affected",
              "version": "54b92e84193749c9968aff2dd46e3b0f42643e18",
              "versionType": "git"
            },
            {
              "lessThan": "a0ab2ba83e35159d81cec830a92e885ecf8139be",
              "status": "affected",
              "version": "54b92e84193749c9968aff2dd46e3b0f42643e18",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/inet_connection_sock.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.14"
            },
            {
              "lessThan": "5.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.216",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.183",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.152",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.104",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.45",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix TFO max_qlen accounting across reuseport migration\n\nA listener\u0027s TCP_FASTOPEN max_qlen stops being accurate and lets through\nfar more pending Fast Open requests than it was configured for.\n\nThis only shows up with SO_REUSEPORT listener migration, where closing a\nlistener hands its still-pending TFO children over to a surviving one.\n\nfastopenq.qlen is charged in tcp_fastopen_create_child() when the child\nis created and uncharged in reqsk_fastopen_remove() when the handshake\ncompletes.  The uncharge follows rsk_listener of the request the child\npoints at, and inet_reqsk_clone() has repointed the child at a new\nrequest owned by the new listener, so the ++ and the -- land on two\ndifferent sockets.  The new listener\u0027s qlen drifts negative and its\nlimit no longer binds.\n\nCharge the new listener during migration, like reqsk_queue_migrated()\nalready does for queue-\u003eyoung and queue-\u003eqlen."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ntcp: corregir la contabilidad de max_qlen de TFO durante la migraci\u00f3n de reuseport\n\nEl max_qlen de TCP_FASTOPEN de un oyente deja de ser preciso y permite el paso de muchas m\u00e1s solicitudes pendientes de Fast Open de las que fue configurado.\n\nEsto solo se manifiesta con la migraci\u00f3n de oyentes SO_REUSEPORT, donde cerrar un oyente entrega sus hijos TFO a\u00fan pendientes a uno sobreviviente.\n\nfastopenq.qlen se carga en tcp_fastopen_create_child() cuando se crea el hijo y se descarga en reqsk_fastopen_remove() cuando el handshake se completa. La descarga sigue a rsk_listener de la solicitud a la que apunta el hijo, e inet_reqsk_clone() ha redirigido al hijo a una nueva solicitud propiedad del nuevo oyente, por lo que el ++ y el -- caen en dos sockets diferentes. El qlen del nuevo oyente se vuelve negativo y su l\u00edmite ya no se aplica.\n\nCargar al nuevo oyente durante la migraci\u00f3n, como ya hace reqsk_queue_migrated() para queue -\u003e young y queue -\u003e qlen."
    }
  ],
  "id": "CVE-2026-74696",
  "lastModified": "2026-10-14T13:10:00.187",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-22T16:16:44.153",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/585fc5247d14939a561056aa2addd9b7c2b1f670"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6e10ee56524a26b250229ad348637825646ddb88"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a0ab2ba83e35159d81cec830a92e885ecf8139be"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a66e869cf0c90c1e47ae75f72b6482acbfc808ff"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b6247e0f96bd825ffb2005257f6177b5e642dee6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d974618b2097453778389d385e3741629c40e0a3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e98f0d80b9cccb5f828425d2004f9686e7d1ae24"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.