Vulnerability · CVE-2023-25136
OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling.
Published Feb 3, 2023 · catalog updated Oct 14, 2026 · OpenSSH server (sshd) 9.1
Check this week
CVE-2023-25136 is not in CISA KEV. FIRST estimates a 89.69% chance of exploitation in the next 30 days. Check whether you run OpenSSH server (sshd) 9.1.
Gaps on this record
- The stored product name is a package slug. The name on this page is taken from the title (OpenSSH server (sshd) 9.1).
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
- Severity
- Medium6.5
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- 89.69%
- Remediation
- Advisory link
- Affected products
- cpe fedoraproject/fedora · cpe netapp/500f firmware · cpe netapp/a250 firmware · cpe netapp/c250 firmware · cpe netapp/ontap select deploy administration utility · cpe openbsd/openssh
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."
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- cpe fedoraproject/fedora37
- cpe fedoraproject/fedora38
- cpe netapp/500f firmwareversion unspecified
- cpe netapp/a250 firmwareversion unspecified
- cpe netapp/c250 firmwareversion unspecified
- cpe netapp/ontap select deploy administration utilityversion unspecified
- cpe openbsd/openssh9.1
How to fix CVE-2023-25136
Recommended remediation
A patch or advisory reference is linked. Open the original publisher for availability by product version.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
CVE-2023-25136 is not in CISA KEV. FIRST estimates a 89.69% chance of exploitation in the next 30 days. Check whether you run OpenSSH server (sshd) 9.1.
Which versions are affected?
Compare what you have installed with 37, 38, 9.1. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
CWE-415: Double Free. EPSS 89.69%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Feb 3, 2023 · NIST NVD
Detected
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."
Oct 14, 2026 · NIST NVD
Updated
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."
Sources
- CVE.orgVulnerability recordCVE-2023-25136
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2023-25136
30-day exploitation probability 89.7%
first.org - NIST NVDVulnerability recordCVE-2023-25136
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
nvd.nist.gov
References
Freshness
Last verified in this catalog Oct 15, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.