Cyber Resilience

CVE-2026-35388

Low

Published: 02 April 2026

Published
02 April 2026
Modified
27 April 2026
KEV Added
—
Patch
—
CVSS Score v3.1 2.5 CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N
EPSS Score 0.0013 2.9th percentile
Risk Priority 15 floored blend · peak EPSS

Summary

CVE-2026-35388 is a low-severity Unprotected Alternate Channel (CWE-420) vulnerability in Openbsd Openssh. Its CVSS base score is 2.5 (Low).

Operationally, exploitation aligns with the MITRE ATT&CK technique SSH (T1021.004); ranked at the 2.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

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

CWE(s)
CWE-420

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1021.004 SSH Lateral Movement
Adversaries may use [Valid Accounts](https://attack.
attack.mitre.org →
T1563.001 SSH Hijacking Lateral Movement
Adversaries may hijack a legitimate user's SSH session to move laterally within an environment.
attack.mitre.org →
Why these techniques?

Omission of multiplexing confirmation in proxy mode directly facilitates unauthorized SSH session attachment or hijacking via OpenSSH multiplexing channels.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

Affected Assets

openbsd
openssh
≤ 10.3

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

AC-17 Remote Access
addresses: CWE-420

Usage restrictions and authorization for remote access protect against unprotected alternate channels.

RA-6 Technical Surveillance Countermeasures Survey
addresses: CWE-420

TSCM surveys detect and neutralize unprotected alternate channels introduced by surveillance equipment or modifications.

SC-41 Port and I/O Device Access
addresses: CWE-420

Removes or disables unprotected alternate I/O channels that could otherwise be used to bypass primary controls.

References