Known exploited vulnerability
CVE-2026-123158
The short answer
CVE-2026-123158 affects OpenBSD OpenSSH and is rated high (CVSS 8.1). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-11-09: attackers are using it, so patch it first. The vendor has linked a patch.
What it is
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.
Weakness: CWE-394.
Severity
8.1 high
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploited (CISA KEV)
Yes, since Nov 9, 2026
Federal due date Nov 12, 2026
EPSS, next 30 days
1.0%
Higher than 63% of scored CVEs
How it can be exploited
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
What CISA says to do
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…
Affected products
OpenSSH. NVD's record lists the exact affected versions.
References
- github.com/leonjza/sshhole-lab ExploitThird Party Advisory
- github.com/openssh/openssh-portable/commit/4353fdc43ef646c43a8dda7025cc1a898caf1482 Patch
- github.com/predkambrij/sshhole-repro ExploitThird Party Advisory
- hachyderm.io/@damienmiller/117563026759098135 Third Party Advisory
- marc.info/?l=openssh-unix-dev&m=179388064263131&w=2 Mailing ListVendor Advisory
- news.ycombinator.com/item?id=50377976 Issue Tracking
- news.ycombinator.com/item?id=50378228 Issue Tracking
- www.openssh.org/releasenotes.html#10.6p2 Release Notes
- alpinelinux.org/posts/2026-11-05-openssh-password-authentication-bypass/ Third Party Advisory
- github.com/coollabsio/coolify/discussions/12484 Third Party Advisory
- github.com/google/goonami-scanner/pull/277 Third Party Advisory
- github.com/panubo/docker-sshd/issues/93 Third Party Advisory
Questions
Is CVE-2026-123158 being exploited?
Yes. CISA added CVE-2026-123158 to its Known Exploited Vulnerabilities catalog on 2026-11-09, with a federal remediation due date of 2026-11-12.
How do I fix CVE-2026-123158?
CISA's 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…
From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.
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