~/exploited / cve-2026-123158

CVE-2026-123158: OpenBSD OpenSSH

According to CISA this vulnerability is already used in attacks (added on 9 November 2026).

Key facts

CVE	CVE-2026-123158
Vendor	OpenBSD — OpenSSH
Vulnerability	OpenBSD OpenSSH Unexpected Status Code or Return Value Vulnerability
Added	9 November 2026
Deadline (US agencies)	12 November 2026
Ransomware campaigns	unknown

Description (CISA)

OpenBSD OpenSSH on Linux contains an unexpected status code or return value vulnerability that could allow for authentication bypass.

Required action (CISA)

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

What admins should do now

Affected? Check whether OpenBSD OpenSSH is in use and which version runs (package manager, admin UI, --version).
Apply the vendor patch or workaround as soon as it exists. If that is not possible right away: restrict outside access (firewall, VPN, reverse proxy).
Review logs back to 9 November 2026: unusual logins, new files, unexpected processes, outbound connections.
If you suspect a compromise: isolate the system, rotate credentials, check the last backup from before the incident.

The deadline applies to US federal agencies. It is still a useful yardstick for everyone: when a flaw is attacked in the wild, waiting is not an option.

Sources

Data: CISA Known Exploited Vulnerabilities Catalog, as of 9 November 2026. No guarantee — always check the vendor's advisory.

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