CVE Catalog

CVE-2026-74696

HighCVSS 7.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.49%

40th percentile - higher than 40% of all known CVEs

Summary

In the Linux kernel, the TCP Fast Open (TFO) implementation has an issue with max_qlen accounting during SO_REUSEPORT listener migration. After migration, the qlen counter is not correctly transferred, causing the limit of pending Fast Open requests to be exceeded.

Risk Assessment

The risk involves potential server overload due to too many pending Fast Open connections, which could lead to denial of service or performance degradation.

Recommendation

It is recommended to update the Linux kernel to a version containing the fix that correctly transfers qlen accounting during socket migration.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS