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 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.
CSIRTS triage
- What
- TCP Fast Open max_qlen accounting fails across reuseport migration, allowing resource exhaustion.
- Who is affected
- Linux systems with TCP Fast Open and reuseport enabled.
- Urgency
- Medium priority; not currently exploited but affects availability.
- Action
- Apply kernel patch for tcp TFO accounting fix.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch CVE-2026-74696
Get an email if CVE-2026-74696 is added to CISA KEV, gains public exploit code, or a new advisory cites it — max one per day, one-click unsubscribe.
Exploitation outlook
- Low exploitation risk0.49% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 40% of all EPSS-scored CVEs.
Advisory coverage (2)
External references
Embed the live status
— this badge updates automatically when the KEV or exploit status changes. How to embed it →
[](https://www.csirts.com/cve/CVE-2026-74696)