tcp: fix TFO max_qlen accounting across reuseport migration

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74696
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:44 UTC
Updated2026-08-25 06:18:53 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.004900000 probability, percentile 0.399250000 (date 2026-08-25)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 54b92e84193749c9968aff2dd46e3b0f42643e18 e98f0d80b9cccb5f828425d2004f9686e7d1ae24 git Not specified
CNA Linux Linux affected 54b92e84193749c9968aff2dd46e3b0f42643e18 b6247e0f96bd825ffb2005257f6177b5e642dee6 git Not specified
CNA Linux Linux affected 54b92e84193749c9968aff2dd46e3b0f42643e18 585fc5247d14939a561056aa2addd9b7c2b1f670 git Not specified
CNA Linux Linux affected 54b92e84193749c9968aff2dd46e3b0f42643e18 6e10ee56524a26b250229ad348637825646ddb88 git Not specified
CNA Linux Linux affected 54b92e84193749c9968aff2dd46e3b0f42643e18 a66e869cf0c90c1e47ae75f72b6482acbfc808ff git Not specified
CNA Linux Linux affected 54b92e84193749c9968aff2dd46e3b0f42643e18 d974618b2097453778389d385e3741629c40e0a3 git Not specified
CNA Linux Linux affected 54b92e84193749c9968aff2dd46e3b0f42643e18 a0ab2ba83e35159d81cec830a92e885ecf8139be git Not specified
CNA Linux Linux affected 5.14 Not specified
CNA Linux Linux unaffected 5.14 semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.152 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.104 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.45 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b6247e0f96bd825ffb2005257f6177b5e642dee6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/585fc5247d14939a561056aa2addd9b7c2b1f670 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e98f0d80b9cccb5f828425d2004f9686e7d1ae24 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6e10ee56524a26b250229ad348637825646ddb88 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a0ab2ba83e35159d81cec830a92e885ecf8139be 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d974618b2097453778389d385e3741629c40e0a3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a66e869cf0c90c1e47ae75f72b6482acbfc808ff 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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