Skip to main content
MEDIUM

CVE-2023-25136

CVSS v3

6.5

MEDIUM

EPSS Score

89.7 %

exploit probability, as of 2026-10-12

CISA KEV

No

known exploited

Exploitation

—

SSVC status

Get an alert for each new CVE published for openssh. Watch openssh in CVE Watch Free account · no credit card

Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • opensshAlmaLinux:9all versions · fixed in 8.7p1-29.el9_2and 4 other packages
  • pam_ssh_agent_authAlmaLinux:9all versions · fixed in 0.10.4-5.29.el9_2

Vendor advisories

  • CVE-2023-25136 Red Hat Product Security114 products fixed

    openssh: the functions order_hostkeyalgs() and list_hostkey_types() leads to double-free vulnerability

  • ICSA-23-348-10 CISA5 known affected

    Siemens SIMATIC S7-1500

    SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) · SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)

  • SSA-398330 Siemens ProductCERT5 known affected

    SSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5

    SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) · SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)

  • RHSA-2023:2645 Red Hat Product Security89 products fixed

    Red Hat Security Advisory: openssh security update

Full record on NVD

Description

OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. This is fixed in OpenSSH 9.2. The double free can be leveraged, by an unauthenticated remote attacker in the default configuration, to jump to any location in the sshd address space. One third-party report states "remote code execution is theoretically possible."

Technical details

Published
2023-02-03

Frequently asked questions

What is CVE-2023-25136?

OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. This is fixed in OpenSSH 9.2. The double free can be leveraged, by an unauthenticated remote attacker in the default configuration, to jump to any location in the sshd address space. One third-party report states "remote code execution is theoretically possible."

Is CVE-2023-25136 actively exploited?

Active exploitation of CVE-2023-25136 has not been confirmed. Its EPSS score was 89.7% on 2026-10-12, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2023-25136?

CVE-2023-25136 has a CVSS v3 base score of 6.5 (MEDIUM severity).

Running openssh? Hear about its next vulnerability

CVE Watch matches each new CVE to the vendors and products you list (vendor and product, not the version) and puts it in your alerts with its KEV and EPSS status.

Get alerts for this productCISA KEV additions, October 2026Search CVEs

Already have an account? Open CVE Watch

No credit card required · 50 free checks/month · Free API key

Go further

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database