What is CVE-2026-35388?

CVE-2026-35388 is a low-severity vulnerability in OpenBSD OpenSSH, classified under Unprotected Alternate Channel. CVSS score: 2.5/10. Published 2026-04-02.

How severe is CVE-2026-35388?

Low severity. CVSS v3 base score is 2.5 out of 10.

Vulnerability in OpenBSD OpenSSH

CVE-2026-35388

OpenSSH before 10.3 omits connection multiplexing confirmation for proxy-mode multiplexing sessions.

Published 2026-04-02 · last modified 2026-07-24.

CVSS v3 metric

CVSS v3 base score 2.5 (Low). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (12.2th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 12th percentile — 12.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.001

Affected products

OpenBSD OpenSSH — versions 0

Weakness classification (CWE)

CWE-420 — Unprotected Alternate Channel

References

www.openssh.org/releasenotes.html (Release Notes)
marc.info/ (Third Party Advisory)
www.openwall.com/lists/oss-security/2026/04/02/3 (Third Party Advisory)

Frequently asked questions

What is CVE-2026-35388?: CVE-2026-35388 is a low-severity vulnerability in OpenBSD OpenSSH, classified under Unprotected Alternate Channel. CVSS score: 2.5/10. Published 2026-04-02.
How severe is CVE-2026-35388?: Low severity. CVSS v3 base score is 2.5 out of 10.