Cyber Resilience

CVE-2026-35387

Openbsd Openssh ≤ 10.3

Published
02 April 2026
Modified
24 July 2026
CVSS Score v3.1 3.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
EPSS Score 0.0024 15th percentile
Risk Priority 15 floored blend · peak EPSS

Summary

CVE-2026-35387 is a low-severity Always-Incorrect Control Flow Implementation (CWE-670) vulnerability in Openbsd Openssh. Its CVSS base score is 3.1 (Low).

Operationally, exploitation aligns with the MITRE ATT&CK technique SSH (T1021.004); ranked at the 15th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-13 (Cryptographic Protection) and AC-17 (Remote Access) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

OpenSSH before 10.3 can use unintended ECDSA algorithms. Listing of any ECDSA algorithm in PubkeyAcceptedAlgorithms or HostbasedAcceptedAlgorithms is misinterpreted to mean all ECDSA algorithms.

CWE(s)
CWE-670

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1021.004 SSH Lateral Movement
Adversaries may use [Valid Accounts](https://attack.
attack.mitre.org →
T1556.004 Network Device Authentication Defense Impairment
Adversaries may use [Patch System Image](https://attack.
attack.mitre.org →
Why these techniques?

Misinterpretation of ECDSA algorithm restrictions in OpenSSH PubkeyAcceptedAlgorithms/HostbasedAcceptedAlgorithms enables unintended key-based authentication over SSH and weakens intended authentication controls.

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

CVEs Like This One

CVE-2026-35414Same product: Openbsd Openssh
CVE-2026-59997Same product: Openbsd Openssh
CVE-2026-59999Same product: Openbsd Openssh
CVE-2026-35388Same product: Openbsd Openssh
CVE-2026-35385Same product: Openbsd Openssh
CVE-2026-59995Same product: Openbsd Openssh
CVE-2026-60000Same product: Openbsd Openssh
CVE-2026-60002Same product: Openbsd Openssh
CVE-2026-59996Same product: Openbsd Openssh
CVE-2026-35386Same product: Openbsd Openssh

Affected Assets

openbsd
openssh
≤ 10.3

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SC-13 Cryptographic Protection
  • CM-7 Least Functionality
  • AC-17 Remote Access
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V9.2.1

Mitigating Controls (NIST 800-53 r5) AI

SC-13 Cryptographic Protection good match
prevent

Directly requires selection and use of only approved cryptographic algorithms for authentication, preventing unintended ECDSA algorithms from being accepted.

CM-7 Least Functionality partial match
prevent

Restricts system functionality to only the specific cryptographic algorithms explicitly required, limiting exposure from the misinterpretation bug.

AC-17 Remote Access partial match
prevent

Enforces control over remote access mechanisms including explicit specification of permitted public-key algorithms in OpenSSH configurations.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly prevent incorrect control-flow implementations via reviews, testing, and static analysis.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
detects

Security testing in development and acceptance can detect paths that deviate from intended logic.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle processes can catch incorrect control-flow logic during design and code review.

A.8.28 Secure coding partial match
prevents

Secure coding standards and reviews directly target flawed control-flow implementations.

A.8.32 Change management partial match
prevents

Change-management gates may prevent deployment of flawed logic but do not address the coding defect itself.

References