OpenBSD OpenSSH Unexpected Status Code or Return Value Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.
Required action
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.
CISA notes
This vulnerability affects an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: https://www.openssh.org/releasenotes.html ; https://alpinelinux.org/posts/2026-11-05-openssh-password-authentication-bypass/ ; https://github.com/openssh/openssh-portable/commit/4353fdc43ef646c43a8dda7025cc1a898caf1482 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-123158
Description
sshd in OpenSSH before 10.6p2 on Linux, when musl libc is used without PAM, lacks a workaround for a password authentication bypass (related to misinterpretation of whether a string is intended to be a password hash). For some configurations of accounts, any password between 256 and 1024 characters succeeds. An example of a platform using musl libc without PAM is Alpine Linux.
Key Findings
as of 2026-11-12- CISA added CVE-2026-123158 to the KEV catalog 4 days after its CVE record was published. The median for entries added in 2026 so far is 12 days.
- It is one of 2 OpenBSD entries in the CISA KEV catalog, and the only one added in 2026.
- Its current EPSS score (18.9%) is higher than that of 32% of CISA KEV entries.
Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HOpen in CVSS calculator Affected Products
| Vendor | Product | Affected versions |
|---|---|---|
| OpenBSD | OpenBSD OpenSSH | 0 to <10.6p2 |
References
14 linksOther references
- https://www.openssh.org/releasenotes.html#10.6p2
- https://github.com/openssh/openssh-portable/commit/4353fdc43ef646c43a8dda7025cc1a898caf1482
- https://news.ycombinator.com/item?id=50377976
- https://news.ycombinator.com/item?id=50378228
- https://marc.info/?l=openssh-unix-dev&m=179388064263131&w=2
- https://hachyderm.io/@damienmiller/117563026759098135
- https://github.com/predkambrij/sshhole-repro
- https://github.com/leonjza/sshhole-lab
- https://alpinelinux.org/posts/2026-11-05-openssh-password-authentication-bypass/
- https://news.ycombinator.com/item?id=50379704
- https://github.com/google/goonami-scanner/pull/277
- https://github.com/coollabsio/coolify/discussions/12484
- https://github.com/panubo/docker-sshd/issues/93
- http://www.openwall.com/lists/oss-security/2026/11/09/27
Record Details
- Published
- 2026-11-05
- Last updated
- 2026-11-10
- Assigner (CNA)
- mitre
- Credited to
- -
CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). Alert titles and links from CISA cybersecurity alerts. This site is not affiliated with or endorsed by MITRE, NVD, CISA, or FIRST.