CVE-2023-25136: OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling.
Noroxi assessment
Priority: Plan (action score 53/100)
- Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
- Probability of exploitation in the next 30 days: 89.7% (FIRST EPSS); higher than 99.7% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: openssh (AlmaLinux:9) 8.7p1-29.el9_2; openssh-askpass (AlmaLinux:9) 8.7p1-29.el9_2; openssh-clients (AlmaLinux:9) 8.7p1-29.el9_2.
Add it to your regular patch cycle. Upgrade to openssh (AlmaLinux:9) 8.7p1-29.el9_2; openssh-askpass (AlmaLinux:9) 8.7p1-29.el9_2; openssh-clients (AlmaLinux:9) 8.7p1-29.el9_2 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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
- Feb 3, 2023
- Updated
- Oct 14, 2026
- EPSS
- 89.7% · 99th percentile
- CWE
- CWE-415
Report tools
Action score
53
Add it to your regular patch cycle.
- CVSS
- 26 / 40 · 6.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 27 / 30 · 89.7%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- Proof of concept exists, no weaponized module
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Is OpenSSH on your server exposed to the internet?Run a port scan
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| openbsd | openssh | cpe:2.3:a:openbsd:openssh |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| 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 | a250 | cpe:2.3:h:netapp:a250 |
| netapp | 500f firmware | cpe:2.3:o:netapp:500f_firmware |
| netapp | 500f | cpe:2.3:h:netapp:500f |
| netapp | c250 firmware | cpe:2.3:o:netapp:c250_firmware |
| netapp | c250 | cpe:2.3:h:netapp:c250 |
Is OpenSSH on your server exposed to the internet?
The free port scanner finds the open ports on your server and matches the service versions it can read against known vulnerabilities. No account needed.
Run a port scanAffected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- fedoraproject fedora37
- fedoraproject fedora38
- netapp 500f firmwareall versions
- netapp a250 firmwareall versions
- netapp c250 firmwareall versions
- netapp ontap select deploy administration utilityall versions
- openbsd openssh9.1
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:9 | openssh | before 8.7p1-29.el9_2 | 8.7p1-29.el9_2 |
| AlmaLinux:9 | openssh-askpass | before 8.7p1-29.el9_2 | 8.7p1-29.el9_2 |
| AlmaLinux:9 | openssh-clients | before 8.7p1-29.el9_2 | 8.7p1-29.el9_2 |
| AlmaLinux:9 | openssh-keycat | before 8.7p1-29.el9_2 | 8.7p1-29.el9_2 |
| AlmaLinux:9 | openssh-server | before 8.7p1-29.el9_2 | 8.7p1-29.el9_2 |
| AlmaLinux:9 | pam_ssh_agent_auth | before 0.10.4-5.29.el9_2 | 0.10.4-5.29.el9_2 |
| Debian:12 | openssh | before 1:9.2p1-1 | 1:9.2p1-1 |
| Red Hat:enterprise_linux:9::appstream | openssh-askpass | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::appstream | openssh-askpass-debuginfo | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::appstream | openssh-clients-debuginfo | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::appstream | openssh-debuginfo | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::appstream | openssh-debugsource | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::appstream | openssh-keycat-debuginfo | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::appstream | openssh-server-debuginfo | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::appstream | openssh-sk-dummy-debuginfo | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::appstream | pam_ssh_agent_auth | before 0:0.10.4-5.29.el9_2 | 0:0.10.4-5.29.el9_2 |
| Red Hat:enterprise_linux:9::appstream | pam_ssh_agent_auth-debuginfo | before 0:0.10.4-5.29.el9_2 | 0:0.10.4-5.29.el9_2 |
| Red Hat:enterprise_linux:9::baseos | openssh | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::baseos | openssh-clients | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::baseos | openssh-keycat | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
| Red Hat:enterprise_linux:9::baseos | openssh-server | before 0:8.7p1-29.el9_2 | 0:8.7p1-29.el9_2 |
Same product
openbsd: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-123158sshd in OpenSSH before 10.6p2 on Linux, when musl libc is used without PAM, lacks a workaround for a password authentication bypass…KEV68This week
- CVE-2023-38408The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 has an insufficiently trustworthy search path, leading to remote code execution if…63This week
- CVE-2018-15473OpenSSH through 7.7 is prone to a user enumeration vulnerability due to not delaying bailout for an invalid authenticating user until after…60This week
Published before and after this one in the same product
- ← EarlierCVE-2021-41617Sep 26, 2021 · sshd in OpenSSH 6.2 through 8.x before 8.8, when certain non-default configurations are used, allows privilege escalation because…29Monitor
- ← EarlierCVE-2021-36368Mar 12, 2022 · An issue was discovered in OpenSSH before 8.9.15Monitor
- Later →CVE-2023-28531Mar 17, 2023 · ssh-add in OpenSSH before 9.3 adds smartcard keys to ssh-agent without the intended per-hop destination constraints.40Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| almalinux:openssh | 8.7p1-29.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:openssh-askpass | 8.7p1-29.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:openssh-clients | 8.7p1-29.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:openssh-keycat | 8.7p1-29.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:openssh-server | 8.7p1-29.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:pam_ssh_agent_auth | 0.10.4-5.29.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| debian:openssh | 1:9.2p1-1 · Debian:12 | Package registry (OSV) |
| red hat:openssh | 0:8.7p1-29.el9_2 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:openssh-askpass | 0:8.7p1-29.el9_2 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:openssh-askpass-debuginfo | 0:8.7p1-29.el9_2 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:openssh-clients | 0:8.7p1-29.el9_2 · Red Hat:enterprise_linux:9::baseos | Package registry (OSV) |
| red hat:openssh-clients-debuginfo | 0:8.7p1-29.el9_2 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:openssh-debuginfo | 0:8.7p1-29.el9_2 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:openssh-debugsource | 0:8.7p1-29.el9_2 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:openssh-keycat-debuginfo | 0:8.7p1-29.el9_2 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:openssh-server-debuginfo | 0:8.7p1-29.el9_2 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:openssh-sk-dummy-debuginfo | 0:8.7p1-29.el9_2 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:pam_ssh_agent_auth | 0:0.10.4-5.29.el9_2 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:pam_ssh_agent_auth-debuginfo | 0:0.10.4-5.29.el9_2 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×11
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | 11 repositories | 2023-02-07 → 2025-11-18 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- First PoC+4 d
- TodayNov 14, 2026+1380 d
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Not on record for this CVE: EPSS history · researcher credit · variant or chain candidate · public bounty program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- none
- Integrity
- low · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- Low
- Availability impact
- High
Weakness class (CWE)
CWE-415 · Double FreeCVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log (1)
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (13 more)Show less
- www.openwall.com/lists/oss-security/2023/02/22/1
- www.openwall.com/lists/oss-security/2023/02/22/2
- www.openwall.com/lists/oss-security/2023/02/23/3
- www.openwall.com/lists/oss-security/2023/03/06/1
- www.openwall.com/lists/oss-security/2023/03/09/2
- ftp.openbsd.org/pub/OpenBSD/patches/7.2/common/017_sshd.patch.sig
- github.com/openssh/openssh-portable/commit/486c4dc3b83b4b67d663fb0fa62bc24138ec3946
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JGAUIXJ3TEKCRKVWFQ6GDAGQFTIIGQQP/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R7LKQDFZWKYHQ65TBSH2X2HJQ4V2THS3/
- news.ycombinator.com/item?id=34711565
- security.gentoo.org/glsa/202307-01
- security.netapp.com/advisory/ntap-20230309-0003/
- cert-portal.siemens.com/productcert/html/ssa-398330.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.