CVE-2023-25136

Exp

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."

Published: 2023-02-03 Last update: 2026-05-28 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-25136 is rated High Exploit Risk (74.6/100): CVSS Medium severity, with high exploitation likelihood (EPSS 88.33%, 99th percentile). 3 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2023-25136

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2023-25136

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-12 89.57% 88.33% -1.24%
2 2026-03-26 91.29% 89.57% -1.72%
3 2026-03-25 — 91.29% —

Full EPSS history (43 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-25136

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 4.2 [email protected]

Weakness enumeration for CVE-2023-25136

OS Trackers for CVE-2023-25136

vendor priority summary link
debian unimportant CVE-2023-25136 unimportant priority: Debian including 1 source packages (openssh), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-25136
gentoo high CVE-2023-25136: 1 GLSA(s) (202307-01), 1 atom(s) (net-misc/openssh); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-25136
redhat medium — https://access.redhat.com/security/cve/CVE-2023-25136
ubuntu medium CVE-2023-25136 medium priority: Ubuntu including 2 source packages (openssh, openssh-ssh1), 26 status rows across 13 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 22, DNE 2, ignored 1, released 1. https://ubuntu.com/security/CVE-2023-25136

Affected software / configurations for CVE-2023-25136

Vendor Product Version Raw CPE
openbsd openssh 9.1 cpe:2.3:a:openbsd:openssh:9.1:*:*:*:*:*:*:*
fedoraproject fedora 37 cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*
fedoraproject fedora 38 cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*
netapp ontap_select_deploy_administration_utility — cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*
netapp a250_firmware — cpe:2.3:o:netapp:a250_firmware:-:*:*:*:*:*:*:*
netapp 500f_firmware — cpe:2.3:o:netapp:500f_firmware:-:*:*:*:*:*:*:*
netapp c250_firmware — cpe:2.3:o:netapp:c250_firmware:-:*:*:*:*:*:*:*

References for CVE-2023-25136

URL Tags
http://www.openwall.com/lists/oss-security/2023/02/13/1 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/02/22/1 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/02/22/2 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/02/23/3 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/03/06/1 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/03/09/2 Mailing List Third Party Advisory
https://bugzilla.mindrot.org/show_bug.cgi?id=3522 Exploit Issue Tracking Third Party Advisory
https://ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017_sshd.patch.sig Patch Vendor Advisory
https://github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946 Patch 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=34711565 Issue Tracking Third Party Advisory
https://security.gentoo.org/glsa/202307-01 Third Party Advisory
https://security.netapp.com/advisory/ntap-20230309-0003/ Third Party Advisory
https://www.openwall.com/lists/oss-security/2023/02/02/2 Exploit Mailing List Third Party Advisory
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