CVE-2026-80586
In the Linux kernel, the following vulnerability has been resolved:
mptcp: options: reset DSS fields in case of unexpected size
A remote peer could send a malformed DSS with a wrong size, followed by
another DSS or MPC + Data. In this case, the first suboption will be
ignored, but leaving some fields written, which could lead to
inconsistency or access uninitialized data.
Explicitly reset the fields that could have been modified in case of
unexpected size.
CSIRTS triage
- What
- MPTCP DSS option handler does not reset fields on unexpected packet size, causing state inconsistency.
- Who is affected
- Systems using MPTCP with untrusted network paths receiving malformed packets.
- Urgency
- Medium priority; malformed MPTCP packets can corrupt connection state and cause DoS.
- Action
- Apply patch resetting MPTCP DSS fields when unexpected packet size is detected.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.40% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 34% of all EPSS-scored CVEs.
Advisory coverage (2)
- criticalCVE-2026-80586: In the Linux kernel, the following vulnerability has been resolved: mptcp: options: reset DSS …nvd · 2026-08-26
- mediumCVE-2026-80586: mptcp: options: reset DSS fields in case of unexpected sizemsrc · 2026-08-11
External references
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