CVE-2023-25136

MEDIUMNVD 6.59.8▲
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2023-02-03. NVD baseline CVSS 6.5; sources differ by 3.3.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Weaponized
6.5
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • 2 internet-exposed hosts are running an affected version right now
  • High exploitation likelihood — EPSS 90%
CISA-KEV: Not listedEPSS: 90%CVSS: 6.5Exploit: NoneExposed: 2

A fix is available — apply it.

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."

Live · internet exposure

2 internet-exposed hosts are running an affected version of CVE-2023-25136 right now.

across 2 countries (China, Poland)top: openssh
See the live KEV-Exposure radar →Found passively from public internet-scan data — aggregate, host-redacted.

EchelonGraph is the only CVE feed that fuses live vulnerability intelligence with its own live internet-exposure radar — so you see not just that a CVE is exploited, but how much of the internet is exposed to it right now.

CVSS v3
6.5
EG Score
9.8(medium)
EG Risk
80(Track)
EG Risk 80/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation90% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
99.8%
KEV
Not listed

Published

February 3, 2023

Last Modified

May 28, 2026

References (32)

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatopenssh-0:8.7p1-29.el9_22023-05-09redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(2)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 3× in last 7d / 16× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 02:19 UTCEG score recompute
  2. 2026-07-22 23:07 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
  4. 2026-07-16 07:19 UTCOSV refresh
  5. 2026-07-15 16:56 UTCEPSS rescore
  6. 2026-07-13 22:28 UTCEPSS rescore
  7. 2026-07-13 22:28 UTCEPSS rescore
  8. 2026-07-11 08:25 UTCEPSS rescore
  9. 2026-07-11 08:25 UTCEPSS rescore
  10. 2026-07-02 16:58 UTCEPSS rescore
  11. 2026-06-28 06:22 UTCOSV refresh
  12. 2026-06-27 03:07 UTCEPSS rescore
  13. 2026-06-24 14:03 UTCEPSS rescore
  14. 2026-06-24 14:03 UTCEPSS rescore
  15. 2026-06-23 21:31 UTCEPSS rescore
  16. 2026-06-23 21:31 UTCEPSS rescore
  17. 2026-06-15 17:47 UTCEPSS rescore
  18. 2026-06-14 23:16 UTCEPSS rescore
  19. 2026-06-12 23:10 UTCEPSS rescore
  20. 2026-06-10 22:17 UTCEPSS rescore
  21. 2026-06-10 17:17 UTCOSV refresh
  22. 2026-06-10 13:21 UTCEPSS rescore
  23. 2026-06-10 13:21 UTCEPSS rescore
  24. 2026-06-08 14:15 UTCEPSS rescore
  25. 2026-06-08 14:15 UTCEPSS rescore
Show 16 more
  1. 2026-06-07 15:23 UTCEPSS rescore
  2. 2026-06-07 15:23 UTCEPSS rescore
  3. 2026-06-05 22:46 UTCEPSS rescore
  4. 2026-06-05 22:46 UTCEPSS rescore
  5. 2026-06-05 22:46 UTCEPSS rescore
  6. 2026-06-05 06:09 UTCEPSS rescore
  7. 2026-06-05 06:09 UTCEPSS rescore
  8. 2026-06-01 13:51 UTCEPSS rescore
  9. 2026-06-01 13:50 UTCEPSS rescore
  10. 2026-05-27 13:39 UTCEPSS rescore
  11. 2026-05-26 07:18 UTCEPSS rescore
  12. 2026-05-26 07:17 UTCEPSS rescore
  13. 2026-05-26 07:17 UTCEPSS rescore
  14. 2026-05-25 07:28 UTCEG score recompute
  15. 2026-05-25 07:28 UTCVendor advisory
  16. 2026-05-25 07:28 UTCGHSA enrichment

Publicly available exploits

(8 references)

Working exploit code is in the public domain (8 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCmalvika-thakur/CVE-2023-25136
    First seen Sep 21, 2023

    OpenSSH Pre-Auth Double Free CVE-2023-25136 – Writeup and Proof-of-Concept

    Open source ↗
  • GitHub PoCH4K6/CVE-2023-25136
    First seen Jun 30, 2023

    OpenSSH 9.1漏洞大规模扫描和利用

    Open source ↗
  • GitHub PoCaxylisdead/CVE-2023-25136_POC
    First seen Jun 3, 2023

    CVE-2023-25136 POC written by axylisdead

    Open source ↗
  • GitHub PoCnhakobyan685/CVE-2023-25136
    First seen Apr 28, 2023

    OpenSSH 9.1 vulnerability mass scan and exploit

    Open source ↗
  • GitHub PoCadhikara13/CVE-2023-25136
    First seen Apr 18, 2023

    OpenSSH Pre-Auth Double Free CVE-2023-25136 POC

    Open source ↗
  • GitHub PoCChristbowel/CVE-2023-25136
    First seen Feb 22, 2023

    OpenSSH 9.1 vulnerability mass scan and exploit

    Open source ↗
  • GitHub PoCticofookfook/CVE-2023-25136
    First seen Feb 14, 2023
    Open source ↗
  • GitHub PoCjfrog/jfrog-CVE-2023-25136-OpenSSH_Double-Free
    First seen Feb 7, 2023
    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2023-25136?
CVE-2023-25136 is a medium vulnerability published on February 3, 2023. 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…
When was CVE-2023-25136 disclosed?
CVE-2023-25136 was first published in the National Vulnerability Database on February 3, 2023, with the most recent update on May 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-25136 actively exploited?
CVE-2023-25136 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2023-25136?
CVE-2023-25136 has a CVSS v3 base score of 6.5 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.8.
How do I remediate CVE-2023-25136?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2023-25136, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2023-25136

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