CVE-2026-80586 (CVSS 9.8)

Description

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.

Is your site exposed to CVE-2026-80586?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0040

Probability of exploitation

0.34%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/15e35fdad7a5576bf3f1c8d688877aeb5d1b506b https://git.kernel.org/stable/c/192878df582c51d440bf7b91a15f297f29f2b596 https://git.kernel.org/stable/c/1fade1b2ac5b1a4948e538fae7313bea57b5ac36 https://git.kernel.org/stable/c/26dac5c9ffb20812b475fdf253eb04fab99cff3b https://git.kernel.org/stable/c/27ed642a4e7e4b5df4b8522c72c457a67e052493 https://git.kernel.org/stable/c/35772b4981f38ba8059372cde8753e8e477e98ec https://git.kernel.org/stable/c/4e80eff5c1c893aca2ac1d202f0b256d2e52ecde https://git.kernel.org/stable/c/b1256090816ec46011601e084be580731df58fc7

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-80586? +

CVE-2026-80586 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0040, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-80586? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-80586