---
title: "CVE-2023-25136: Double Free | CubePath"
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…"
language: en
source: https://cubepath.com/security/cve/CVE-2023-25136
---

# CVE-2023-25136: Double Free | CubePath

## 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](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2023-25136)

## Key data

### EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.

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

Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA.

Exploitation

Public proof of concept recorded by CISA

Automatable

no

Technical impact

partial

### Weakness (CWE)

CWE catalog version 5.0.

CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license.

- [CWE-415](https://cwe.mitre.org/data/definitions/415.html) Double Free

## References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

- [ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017\_sshd.pat…](https://ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017%5Fsshd.patch.sig)
- [openwall.com/lists/oss-security/2023/02/02/2](https://www.openwall.com/lists/oss-security/2023/02/02/2)
- [bugzilla.mindrot.org/show\_bug.cgi?id=3522](https://bugzilla.mindrot.org/show%5Fbug.cgi?id=3522)
- [github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67…](https://github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946)
- [jfrog.com/blog/openssh-pre-auth-double-free-cve-2023-25136-…](https://jfrog.com/blog/openssh-pre-auth-double-free-cve-2023-25136-writeup-and-proof-of-concept/)
- [news.ycombinator.com/item?id=34711565](https://news.ycombinator.com/item?id=34711565)
- [\[oss-security\] 20230213 Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)](http://www.openwall.com/lists/oss-security/2023/02/13/1)  (openwall.com) mailing-list
- [\[oss-security\] 20230222 Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)](http://www.openwall.com/lists/oss-security/2023/02/22/1)  (openwall.com) mailing-list
- [\[oss-security\] 20230222 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)](http://www.openwall.com/lists/oss-security/2023/02/22/2)  (openwall.com) mailing-list
- [\[oss-security\] 20230223 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)](http://www.openwall.com/lists/oss-security/2023/02/23/3)  (openwall.com) mailing-list
- [\[oss-security\] 20230306 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)](http://www.openwall.com/lists/oss-security/2023/03/06/1)  (openwall.com) mailing-list
- [\[oss-security\] 20230309 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)](http://www.openwall.com/lists/oss-security/2023/03/09/2)  (openwall.com) mailing-list
- [security.netapp.com/advisory/ntap-20230309-0003](https://security.netapp.com/advisory/ntap-20230309-0003/)
- [FEDORA-2023-1176c8b10c](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R7LKQDFZWKYHQ65TBSH2X2HJQ4V2THS3/)  (lists.fedoraproject.org) vendor-advisory
- [FEDORA-2023-123647648e](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JGAUIXJ3TEKCRKVWFQ6GDAGQFTIIGQQP/)  (lists.fedoraproject.org) vendor-advisory
- [GLSA-202307-01](https://security.gentoo.org/glsa/202307-01)  (security.gentoo.org) vendor-advisory

## Timeline

1. ID reserved Feb 3, 2023
2. Record published Feb 3, 2023
3. Record last updated Oct 14, 2026

## Look up another CVE

## About CubePath

CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection.

[Cloud VPS](https://cubepath.com/vps) [DDoS protection](https://cubepath.com/ddos-protection)

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, 20:01 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)