CVE-2026-123158: openssh — Actively Exploited & Fix

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.

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CVSS v3.1 Score

8.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.1890

Probability of exploitation

0.97%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

CISA Known Exploited Vulnerability

This vulnerability is actively exploited in the wild.

Added: Nov 9, 2026 Remediation due: Nov 12, 2026

Weakness Type (CWE)

CWE-394 CWE-394

Affected Products

Vendor	Product	Versions
openbsd	openssh	< 10.6
openbsd	openssh	All
openbsd	openssh	All
alpinelinux	alpine_linux	< 3.21.10
alpinelinux	alpine_linux	3.22.0 — 3.22.8
alpinelinux	alpine_linux	3.23.0 — 3.23.8
alpinelinux	alpine_linux	3.24.0 — 3.24.4

References

Advisories & Patches

https://github.com/openssh/openssh-portable/commit/4353fdc43ef646c43a8dda7025cc1a898caf1482 https://marc.info/?l=openssh-unix-dev&m=179388064263131&w=2

Exploits

https://github.com/leonjza/sshhole-lab https://github.com/predkambrij/sshhole-repro

Other References

https://hachyderm.io/@damienmiller/117563026759098135 https://news.ycombinator.com/item?id=50377976 https://news.ycombinator.com/item?id=50378228 https://www.openssh.org/releasenotes.html#10.6p2 http://www.openwall.com/lists/oss-security/2026/11/09/27 https://alpinelinux.org/posts/2026-11-05-openssh-password-authentication-bypass/ https://github.com/coollabsio/coolify/discussions/12484 https://github.com/google/goonami-scanner/pull/277 https://github.com/panubo/docker-sshd/issues/93 https://news.ycombinator.com/item?id=50379704

Frequently Asked Questions

What is CVE-2026-123158? +

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. It has a CVSS v3.1 base score of 8.1 (HIGH). This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.

How severe is CVE-2026-123158? +

CVE-2026-123158 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.1890, placing it in the 1th percentile for exploitation probability.

What products are affected by CVE-2026-123158? +

CVE-2026-123158 affects products from alpinelinux, openbsd, specifically: alpine_linux, openssh. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-123158? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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