HOME VULNERABILITIESCVE-2023-25136

MEDIUM

CVE-2023-25136

CWE-415Published: February 3, 2023· Updated: Jun 17, 2026

6.5

CVSS v3.1

Official 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 Analysis

CVE-2023-25136 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges Req.None

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityHigh

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected Vendors & Products

Fedora1 product(s)

fedora

netapp7 product(s)

ontap select deploy administration utilitya250 firmwarea250500f firmware500fc250 firmwarec250

openbsd1 product(s)

openssh

Source: NVD CPE · 10 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time

Offensive Security exploit database

GitHub PoC Search

Community PoC repositories

Rapid7 / Metasploit

Metasploit module search

Security advisories & exploits

Official NIST entry

CVE Program entry

External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017_sshd.patch.sig

PATCHhttps://github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946

PATCHhttps://ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017_sshd.patch.sig

PATCHhttps://github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/02/13/1

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/02/22/1

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/02/22/2

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/02/23/3

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/03/06/1

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/03/09/2

ADVISORYhttps://bugzilla.mindrot.org/show_bug.cgi?id=3522

ADVISORYhttps://jfrog.com/blog/openssh-pre-auth-double-free-cve-2023-25136-writeup-and-proof-of-concept/

ADVISORYhttps://news.ycombinator.com/item?id=34711565

ADVISORYhttps://security.gentoo.org/glsa/202307-01

ADVISORYhttps://security.netapp.com/advisory/ntap-20230309-0003/

ADVISORYhttps://www.openwall.com/lists/oss-security/2023/02/02/2

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/02/13/1

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/02/22/1

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/02/22/2

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/02/23/3

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/03/06/1

ADVISORYhttp://www.openwall.com/lists/oss-security/2023/03/09/2

ADVISORYhttps://bugzilla.mindrot.org/show_bug.cgi?id=3522

ADVISORYhttps://jfrog.com/blog/openssh-pre-auth-double-free-cve-2023-25136-writeup-and-proof-of-concept/

ADVISORYhttps://news.ycombinator.com/item?id=34711565

ADVISORYhttps://security.gentoo.org/glsa/202307-01

ADVISORYhttps://security.netapp.com/advisory/ntap-20230309-0003/

ADVISORYhttps://www.openwall.com/lists/oss-security/2023/02/02/2

All References (32)

→

http://www.openwall.com/lists/oss-security/2023/02/13/1Mailing List · Third Party Advisory

→

http://www.openwall.com/lists/oss-security/2023/02/22/1Mailing List · Third Party Advisory

→

http://www.openwall.com/lists/oss-security/2023/02/22/2Mailing List · Third Party Advisory

→

http://www.openwall.com/lists/oss-security/2023/02/23/3Mailing List · Third Party Advisory

→

http://www.openwall.com/lists/oss-security/2023/03/06/1Mailing List · Third Party Advisory

→

http://www.openwall.com/lists/oss-security/2023/03/09/2Mailing List · Third Party Advisory

→

https://bugzilla.mindrot.org/show_bug.cgi?id=3522Exploit · Issue Tracking · Third Party Advisory

→

https://ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017_sshd.patch.sigPatch · Vendor Advisory

→

https://github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946Patch · Third Party Advisory

→

https://jfrog.com/blog/openssh-pre-auth-double-free-cve-2023-25136-writeup-and-proof-of-concept/Exploit · Third Party Advisory

→

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JGAUIXJ3TEKCRKVWFQ6GDAGQFTIIGQQP/

→

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R7LKQDFZWKYHQ65TBSH2X2HJQ4V2THS3/

→

https://news.ycombinator.com/item?id=34711565Issue Tracking · Third Party Advisory

→

https://security.gentoo.org/glsa/202307-01Third Party Advisory

→

https://security.netapp.com/advisory/ntap-20230309-0003/Third Party Advisory

Quick Facts

CVE IDCVE-2023-25136

CVSS Score6.5 / 10

SeverityMEDIUM

WeaknessCWE-415

CISA KEVNo

Affected3 vendor(s)

PublishedFeb 3, 2023

Related CVEs (CWE-415)

Recommended Actions

→Apply vendor patches immediately
→Monitor CVE-2023-25136 in threat intel feeds
→Review IDS/IPS signatures for exploitation attempts

Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.

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