OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. This is fixed in OpenSSH 9.2. The…

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."

Scores

EPSS (exploitation in 30 days)

89.8% · top 0.2% of all CVEs (6 Nov 2026)

CISA SSVC

Exploitation: poc · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.

Weakness

• n/a
• CWE-415 Double Free (opens in a new tab)All about CWE-415 and its CVEs

Affected products

• n/a

  • affected n/a

References (17)

• https://ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017_sshd.patch.sig (opens in a new tab)x_transferred
• https://www.openwall.com/lists/oss-security/2023/02/02/2 (opens in a new tab)x_transferred
• https://bugzilla.mindrot.org/show_bug.cgi?id=3522 (opens in a new tab)x_transferred
• https://github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946 (opens in a new tab)x_transferred
• https://jfrog.com/blog/openssh-pre-auth-double-free-cve-2023-25136-writeup-and-proof-of-concept/ (opens in a new tab)x_transferred
• https://news.ycombinator.com/item?id=34711565 (opens in a new tab)x_transferred
• [oss-security] 20230213 Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (opens in a new tab)mailing-listx_transferred
• [oss-security] 20230222 Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (opens in a new tab)mailing-listx_transferred
• [oss-security] 20230222 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (opens in a new tab)mailing-listx_transferred
• [oss-security] 20230223 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (opens in a new tab)mailing-listx_transferred
• [oss-security] 20230306 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (opens in a new tab)mailing-listx_transferred
• [oss-security] 20230309 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (opens in a new tab)mailing-listx_transferred
• https://security.netapp.com/advisory/ntap-20230309-0003/ (opens in a new tab)x_transferred
• FEDORA-2023-1176c8b10c (opens in a new tab)vendor-advisoryx_transferred
• FEDORA-2023-123647648e (opens in a new tab)vendor-advisoryx_transferred
• GLSA-202307-01 (opens in a new tab)vendor-advisoryx_transferred
• https://cert-portal.siemens.com/productcert/html/ssa-398330.html (opens in a new tab)

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2023-25136](https://trackcve.app/badge/CVE-2023-25136.svg)](https://trackcve.app/cve/CVE-2023-25136)

Record last updated 14 Oct 2026, 22:32 UTC.