CVE-2026-74696
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.49%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.49% probability · 41th percentile
- CISA KEV
- Not listed
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/585fc5247d14939a561056aa2addd9b7c2b1f670
- https://git.kernel.org/stable/c/6e10ee56524a26b250229ad348637825646ddb88
- https://git.kernel.org/stable/c/a0ab2ba83e35159d81cec830a92e885ecf8139be
- https://git.kernel.org/stable/c/a66e869cf0c90c1e47ae75f72b6482acbfc808ff
- https://git.kernel.org/stable/c/b6247e0f96bd825ffb2005257f6177b5e642dee6
- https://git.kernel.org/stable/c/d974618b2097453778389d385e3741629c40e0a3
- https://git.kernel.org/stable/c/e98f0d80b9cccb5f828425d2004f9686e7d1ae24
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.