🛡️ CVE-2023-25136 — 500f-firmware

🟡 CVSS 6.5 — Medium ⚠️ Exploit Public CWE-415 NVD

6.5

CVSS Score

0 Low4 Medium7 High9 Critical10

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."

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity low, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

Attack vector: Network — reachable from anywhere that can route to the service.
Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
Privileges required: None — an unauthenticated stranger can try it.
User interaction: None — nobody has to be tricked into anything.
Scope: Unchanged — the damage stays inside the vulnerable component.
Confidentiality impact: None.
Integrity impact: Low — limited, and the attacker does not choose what is affected.
Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2023-25136 is classified as CWE-415: Double Free. The same allocation is released twice, corrupting allocator bookkeeping.

Affected software

CVE-2023-25136 is recorded against 6 packages.

500f-firmware
a250-firmware
c250-firmware
fedora
ontap-select-deploy-administration-utility
openssh

Timeline and source

Published on 3 February 2023 and last revised on 17 June 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from NVD.

References

Other advisories for this package

500f-firmware has other advisories on record. If you are patching this one, these are worth checking on the same host:

CVE-2024-6119 (7.5 High, published 3 Sep 2024)
CVE-2024-6387 (8.1 High, published 1 Jul 2024)
CVE-2024-1086 (7.8 High, published 31 Jan 2024)
CVE-2022-0778 (7.5 High, published 15 Mar 2022)

Same weakness in other software

These advisories are the same class of weakness (CWE-415: Double Free) in other software:

CVE-2023-25801 (8.0 High, published 13 Jul 2026)
CVE-2025-12343 (3.3 Low, published 18 Feb 2026)
CVE-2025-13844 (5.3 Medium, published 15 Jan 2026)
CVE-2025-47396 (7.8 High, published 7 Jan 2026)
CVE-2025-47356 (7.8 High, published 7 Jan 2026)
CVE-2025-20781 (7.8 High, published 6 Jan 2026)
CVE-2025-20801 (7.0 High, published 6 Jan 2026)
CVE-2025-20786 (6.7 Medium, published 6 Jan 2026)

CVE-2023-25136 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

BellSoft — BELL-CVE-2023-25136 Debian — DEBIAN-CVE-2023-25136 Ubuntu — UBUNTU-CVE-2023-25136

Details

Severity MEDIUM

CVSS Score 6.5

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

CWE CWE-415

Public Exploit ⚠️ Yes

Source NVD

Published 2023-02-03

Updated 2026-08-20

Modified 2026-06-17

Fix URL https://ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017_sshd.patch.sig

Affected Packages

Software	From version	Fixed in
500f-firmware	—	—
a250-firmware	—	—
c250-firmware	—	—
fedora	—	—
ontap-select-deploy-administration-utility	—	—
openssh	—	—

References

Mailing List, Third Party Advisory 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

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

Patch, Vendor Advisory https://ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017_sshd.patch.sig

Patch, Third Party Advisory https://github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946

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

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/

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

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

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

Exploit, Mailing List, Third Party Advisory https://www.openwall.com/lists/oss-security/2023/02/02/2

Mailing List, Third Party Advisory 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

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

Patch, Vendor Advisory https://ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017_sshd.patch.sig

Patch, Third Party Advisory https://github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946

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

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/

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

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

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

Exploit, Mailing List, Third Party Advisory https://www.openwall.com/lists/oss-security/2023/02/02/2

🔗 NVD 🔗 Mitre ✅ Fix / Advisory

Similar Threats

Exploit Protection

Are you running 500f-firmware?

CVE-2023-25136 carries CVSS 6.5 Medium rating and a public exploit already exists. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

Check My Site For CVE-2023-25136 →

No credit card required · Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

🛡️ CVE-2023-25136 — 500f-firmware

Description

How this vulnerability can be exploited

CVSS metrics in full

Weakness class

Affected software

Timeline and source

References

Other advisories for this package

Same weakness in other software

CVE-2023-25136 on other distributions

Are you running 500f-firmware?

Browse related advisories

Company

Resources

Services

Trusted

Subscribe