CVE-2026-80585 Affecting kernel-source package, versions <6.4.0-150700.53.84.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.31% (23rd percentile)

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  • Snyk IDSNYK-SLES157-KERNELSOURCE-21167870
  • published17 Oct 2026
  • disclosed16 Oct 2026

Introduced: 16 Oct 2026

NewCVE-2026-80585  (opens in a new tab)

How to fix?

Upgrade SLES:15.7 kernel-source to version 6.4.0-150700.53.84.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-source package and not the kernel-source package as distributed by SLES. See How to fix? for SLES:15.7 relevant fixed versions and status.

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.

mptcp_fastopen_subflow_synack_set_params() set is_mptfo before checking for queued SYN data. That made data-less TFO SYNs hit a WARN and, if the warning was non-fatal, left stale MPTFO state behind. The stale flag could later trigger a state-confusion bug in check_fully_established().

Only mark the subflow as MPTFO after confirming that an SKB was queued. Return quietly when the receive queue is empty.

Note that mptcp_subflow_context's is_mptfo field is now not just about subflows where the TFO was present, but about MPTFO subflow that consumed SYN data. Only having a valid cookie but not carrying data is not really "doing TFO".

CVSS Base Scores

version 3.1