CVE-2023-25136
Double Free
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."
Official description from the CVE record, published by mitre. Copyright © 1999-2026 The MITRE Corporation. See /security/cve/legal for the CVE license. View the record on cve.org
Key data
EPSS
- Score
- 0.89792 (89.8% probability)
- Percentile
- 99.8%
- Scores of
- Nov 10, 2026
- Model
- v2026.06.15
CISA assessment as of Feb 27, 2024
- Exploitation
- Public proof of concept recorded by CISA
- Automatable
- no
- Technical impact
- partial
Weakness (CWE)
- CWE-415Double Free
References
- ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017_sshd.pat…
- openwall.com/lists/oss-security/2023/02/02/2
- bugzilla.mindrot.org/show_bug.cgi?id=3522
- github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67…
- jfrog.com/blog/openssh-pre-auth-double-free-cve-2023-25136-…
- news.ycombinator.com/item?id=34711565
- [oss-security] 20230213 Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (openwall.com)mailing-list
- [oss-security] 20230222 Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (openwall.com)mailing-list
- [oss-security] 20230222 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (openwall.com)mailing-list
- [oss-security] 20230223 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (openwall.com)mailing-list
- [oss-security] 20230306 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (openwall.com)mailing-list
- [oss-security] 20230309 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136) (openwall.com)mailing-list
- security.netapp.com/advisory/ntap-20230309-0003
- FEDORA-2023-1176c8b10c (lists.fedoraproject.org)vendor-advisory
- FEDORA-2023-123647648e (lists.fedoraproject.org)vendor-advisory
- GLSA-202307-01 (security.gentoo.org)vendor-advisory
Timeline
- ID reserved
- Record published
- Record last updated
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About CubePath
Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 19:49 UTC. Sources and licenses