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…
- 6.5MediumCVSS base score
- 89.8%Exploitation in 30 daysEPSS · top 0.2% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- YesPublic exploitsa reference or SSVC says so
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."
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: a proof of concept is public.
Timeline
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H |
- EPSS (exploitation in 30 days)
- 89.8% · top 0.2% of all CVEs (11 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.
Affected products
n/a
- affected n/a
References
References17
- 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)
- EUVD EUVD-2023-29115 (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
[](https://cveledger.app/cve/CVE-2023-25136)Record last updated .