OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during…
Priority HIGH 71CWE-415Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
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."
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.89792 99th percentileScored 2026-11-07
Public exploit Yes 3 exploit referencesTagged by NVD
Fix Fixed Red Hat: 1 advisory
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 10
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:openbsd:openssh:9.1:*:*:*:*:*:*:* | 9.1 | Vulnerable | OpenBSD |
| cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:* | 37 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:* | 38 | Vulnerable | Fedoraproject |
| cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:o:netapp:a250_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:a250:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:o:netapp:500f_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:500f:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
| cpe:2.3:o:netapp:c250_firmware:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
| cpe:2.3:h:netapp:c250:-:*:*:*:*:*:*:* | not specified by NVD | Running on | NetApp |
- cpe:2.3:a:openbsd:openssh:9.1:*:*:*:*:*:*:* Versions 9.1 Vulnerable ·OpenBSD
- cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:* Versions 37 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:* Versions 38 Vulnerable ·Fedoraproject
- cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:o:netapp:a250_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:a250:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:o:netapp:500f_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:500f:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
- cpe:2.3:o:netapp:c250_firmware:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
- cpe:2.3:h:netapp:c250:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·NetApp
Remediation
Red Hat 1 advisory
- RHSA-2023:2645 Released 2023-05-09 · Red Hat rating Moderateopenssh security update
- Red Hat Enterprise Linux AppStream (v. 9) openssh-askpass-8.7p1-29.el9_2, pam_ssh_agent_auth-0.10.4-5.29.el9_2
- Red Hat Enterprise Linux BaseOS (v. 9) openssh-8.7p1-29.el9_2, openssh-clients-8.7p1-29.el9_2, openssh-keycat-8.7p1-29.el9_2 +1
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2023:2645 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2023:2645 |
Not affected: 3 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
Timeline
- 2026-10-02 Threatist record created from CVE-2023-25136
- 2026-10-03 Alias added: GHSA-w62j-g234-3f6f
References
Exploit 3
Patch 2
Advisory 11
- https://news.ycombinator.com/item?id=34711565
- [oss-security] 20230213 Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)
- [oss-security] 20230222 Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)
- [oss-security] 20230222 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)
- [oss-security] 20230223 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)
- [oss-security] 20230306 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)
- [oss-security] 20230309 Re: Re: double-free vulnerability in OpenSSH server 9.1 (CVE-2023-25136)
- https://security.netapp.com/advisory/ntap-20230309-0003/
- FEDORA-2023-1176c8b10c
- FEDORA-2023-123647648e
- GLSA-202307-01
Sources
- CVE-2023-25136 · CVE Program
- CVE-2023-25136 · NVD
- FIRST EPSS
- GHSA-w62j-g234-3f6f · GitHub Advisory Database · CC BY 4.0
- CVE-2023-25136 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences