8.1

CVE-2026-123158: OpenBSD OpenSSH Unexpected Status Code or Return Value Vulnerability

KEV
Analyzed
AliasesALPINE-CVE-2026-123158DEBIAN-CVE-2026-123158UBUNTU-CVE-2026-123158
Published 05-11-2026Last modified 10-11-2026

Vulnerability summary

CVE-2026-123158 is a high (CVSS 8.1) Unexpected Status Code or Return Value vulnerability in OpenBSD OpenSSH. It is known to be exploited: CISA lists it, first on 09-11-2026. EPSS estimates a 16.50% chance of exploitation in the next 30 days, higher than 97% of scored vulnerabilities. 3 public exploits are recorded.

Priority
Act nowlisted as exploited

Listed as exploited by CISA (09-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
8.1/10
010
High · v3.1 (CVE.org)
EPSS score
16.50%
0%100%
Medium · Change unavailable
KEVExploited in the wildCritical · listed in 1 catalog
RansomwareNot flaggedNo ransomware use recorded.
Public exploits3reference, github

Timeline

  1. 05-11-2026
    PublishedVulnerability first disclosed.
  2. 09-11-2026
    Added to CISA KEVExploitedOpenBSD OpenSSH Unexpected Status Code or Return Value Vulnerability
  3. 10-11-2026
    Last modifiedVulnerability information updated.
  4. 12-11-2026
    CISA remediation dueUpcomingApply mitigations per vendor instructions.

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.

CVSS metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

16.50%

Chance of exploitation in the next 30 days

Percentile

97%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

06-11-202610-11-2026

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
09-11-2026
Federal due date
12-11-2026
ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

CISA 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. alpinelinux.org/posts/2026-11-05-openssh-password-authentication-bypass/ github.com/openssh/openssh-portable/commit/4353fdc43ef646c43a8dda7025cc1a898caf1482 nvd.nist.gov/vuln/detail/CVE-2026-123158

Public exploits

3 found
  • referenceUnverified

    Exploit Reference (sshhole.com)

    Maturity: unknown

  • githubUnverified

    Sshhole Repro

    Maturity: poc

  • githubUnverified

    Sshhole Lab

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu3 products
  • opensshAll versions (No fix recorded)
  • openssh-gssapiAll versions (No fix recorded)
  • openssh-ssh1All versions (No fix recorded)
Debian2 products
  • opensshAll versions (No fix recorded) | < 1:10.6p2-1
  • openssh-gssapiAll versions (No fix recorded) | < 1:10.6p2-1
Alpine1 product
  • openssh< 9.0_p1-r6 | < 9.1_p1-r7 | < 9.3_p2-r4 | < 9.6_p1-r3 | < 9.7_p1-r6 | < 9.9_p2-r1 | < 10.0_p1-r11 | < 10.2_p1-r1 | < 10.3_p1-r2
Openbsd1 product
  • openssh< 10.6p2 | < 10.6 | 10.6 | 10.6:p1

4 vendors · 7 products

References

24 links
Show all 24 references