CVE-2026-80585

A flaw was found in the Linux kernel. In the Multipath TCP MPTCP Fast Open feature, a vulnerability exists where the system incorrectly marks a subflow as MPTFO even when a TCP Fast Open TFO SYN packet does not contain data. This can lead to a stale MPTFO state, potentially triggering a...

EUVD-2026-66500

In the Linux kernel, the following vulnerability has been resolved: mptcp: fastopen: only mark MPTFO subflows with SYN data Passive TCP Fast Open accepts a valid-cookie SYN even when it carries no data. In that case the child socket's receive queue is intentionally left empty...

CVE-2026-80585

This vulnerability affects the Linux kernel's MPTCP (Multipath TCP) Fast Open implementation. The function mptcp_fastopen_subflow_synack_set_params() incorrectly set the is_mptfo flag before verifying that SYN data had actually been queued on the child socket's receive queue. Data-less TFO SYNs (...