HighCVE-2026-123158

OpenSSH: Unexpected Status Code or Return Value (CVE-2026-123158)

Published 06.11.2026Sources: BSI

Actively exploited
Source: VulnCheck KEV (opens in a new tab), ANSSI / CERT-FR How we classify

What is affected, what to do

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.

The vulnerability is being actively exploited; treat it as a priority. Update OpenBSD OpenSSH to version 10.6p2.

Affected: OpenBSD OpenSSH lt *..10.6p2
Fixed in: OpenBSD OpenSSH 10.6p2

Not sure whether and how you are affected? Ask a question about this vulnerability

Metrics

8.1

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: Vendor (CNA), CVSS v3

8.1

CVSS v3

Severity High on the scale from 0 to 10.

Source: BSI

1.0 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 62.3

Show all metrics

Severity: High
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 101.53 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: actively exploitedSource: VulnCheck KEV (opens in a new tab), ANSSI / CERT-FR How we classify
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 8.1 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 8.1
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 1.0 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 62.3; High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 06.11.2026
CISA assessment (SSVC): Exploitation: proof of concept · not automatable · Technical impact: total; Source: CISA Vulnrichment, as of 5 November 2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-394

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

Source: BSI WID Portal

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
OpenBSD	OpenSSH	`< 10.6p2`	`10.6p2`
Open Source	OpenSSH	`< 10.6p2`	`10.6p2`

From bundled advisories, not CVE-specific (2)

Product list of a bundled advisory that does not state which product this CVE affects.

Products from bundled advisories
		Affected versions	Fixed in
—	OpenSSH sshd on Alpine Linux (openssh-server, built without PAM)	`Alpine Linux 3.16 through 3.24 and edge: openssh-server (no PAM), or openssh-server-pam with UsePAM no, with PasswordAuthenticat` `Official Alpine tiny-cloud images 3.18.11 through 3.24.3 (alpine user with * password and passwordless doas) once any $6$ hash e`	— —

Vendors and products

Weakness classes (CWE)

CWE-394Unexpected Status Code or Return Value
Base
The product does not properly check when a function or operation returns a value that is legitimate for the function, but is not expected by the product.
Entry at MITRE CWE-394

Public exploit references

Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

Public exploit references

ANSSI / CERT-FRLicence Ouverte 2.0, as of 05.11.2026	CERTFR-2026-ALE-015 – [MàJ] Vulnérabilité dans OpenSSH (opens in a new tab)cert.cyber.gouv.fr	actively exploited	05.11.2026

References & sources

github.comleonjza/sshhole-lab
github.comopenssh-portable fix commit 4353fdcpwn-watch
github.compredkambrij/sshhole-repro
hachyderm.io@damienmiller/117563026759098135
marc.info?l=openssh-unix-dev&m=179388064263131&w=2
news.ycombinator.comitem?id=50377976
news.ycombinator.comitem?id=50378228
openssh.orgreleasenotes.html
pwn.watchpwn.watch: Alpine Linux sshd password authentication bypass lets anyone log in to key-only accounts (CVE-2026-123158)pwn-watch
alpinelinux.orgSecurity advisory: openssh-server password authentication bypasspwn-watch
openssh.orgOpenSSH 10.6p2 release notespwn-watch
CVE.org (MITRE)CVE-2026-123158pwn-watch
news.ycombinator.comAlpine Linux Security Advisory: OpenSSH-server password authentication bypasspwn-watch
sshhole.com*sshole — OpenSSH on musl password authentication bypasspwn-watch, Exploit
NVD (NIST)CVE-2026-123158 (NVD)pwn-watch
status.linode.comCustomer Security Advisory: OpenSSH Password Authentication Bypass Vulnerabilitypwn-watch
openssh.orgOpenSSH 10.6p2 portable release notespwn-watch
bleepingcomputer.comOpenSSH flaw lets attackers log into password-disabled Linux accountspwn-watch
orca.security*sshole: OpenSSH Authentication Bypass Gives Attackers Root on Alpine Linuxpwn-watch
theregister.comGet root on a musl Linux system by slamming it with an overly long passwordpwn-watch

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

06.11.2026Record modifiedCISA ADP

CISA assessment (SSVC): exploitation: proof of concept, automatable: no

Show 2 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
SSVC assessment	removed	{"id":"CVE-2026-123158","role":"CISA Coordinator","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-11-05T17:12:53.200399Z"}	—
SSVC assessment	added	—	{"id":"CVE-2026-123158","role":"CISA Coordinator","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-11-05T00:00:00+00:00"}

Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

05.11.2026Record modifiedCVE Program
New references:
- https://github.com/google/goonami-scanner/pull/277
Show the original change
Individual changes of this event as published by NVD
Type Action Before After
Reference added
—
https://github.com/google/goonami-scanner/pull/277
Source identifier: af854a3a-2127-422b-91ae-364da2661108

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://github.com/google/goonami-scanner/pull/277

05.11.2026Record modifiedCISA ADP

CISA assessment (SSVC): exploitation: proof of concept, automatable: no

New references:

https://sshhole.com

Show 2 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://sshhole.com
SSVC assessment	added	—	{"id":"CVE-2026-123158","role":"CISA Coordinator","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-11-05T17:12:53.200399Z"}

Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

05.11.2026Record modifiedCVE Program

New references:

Show 2 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://alpinelinux.org/posts/2026-11-05-openssh-password-authentication-bypass/
Reference	added	—	https://news.ycombinator.com/item?id=50379704

Source identifier: af854a3a-2127-422b-91ae-364da2661108

05.11.2026ReceivedMITRE

CVSS V3.1: AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness type: CWE-394

Description added or changed

New references:

and 4 more references

Show 12 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Description	added	—	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.
CVSS	added	—	AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness type (CWE)	added	—	CWE-394
Affected versions (publisher)	added	—	New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/123xxx/CVE-2026-123158.json">CVE-2026-123158</a>
Reference	added	—	https://github.com/leonjza/sshhole-lab
Reference	added	—	https://github.com/openssh/openssh-portable/commit/4353fdc43ef646c43a8dda7025cc1a898caf1482
Reference	added	—	https://github.com/predkambrij/sshhole-repro
Reference	added	—	https://hachyderm.io/@damienmiller/117563026759098135
Reference	added	—	https://marc.info/?l=openssh-unix-dev&m=179388064263131&w=2
Reference	added	—	https://news.ycombinator.com/item?id=50377976
Reference	added	—	https://news.ycombinator.com/item?id=50378228
Reference	added	—	https://www.openssh.org/releasenotes.html#10.6p2

Source identifier: cve@mitre.org

Linked CVEs

Linked CVEs

High	CVE-2026-123158	OpenBSD OpenSSH: Unexpected Status Code or Return Value	8.1	—

Linked advisories

Hackers Target OpenSSH SSHole Flaw Within Hours of Disclosure, Gain Root on HoneypotThe Hacker News06.11.2026
OpenSSH flaw lets attackers access password-disabled accounts on some Linux systemsCSO Online06.11.2026

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