CVE-2026-55653

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 84% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

A fix is available — apply it.

A flaw was found in OpenSSH. A malicious SSH server can exploit a double free vulnerability in the Diffie-Hellman Group Exchange (DH-GEX) client path. This occurs during FIPS (Federal Information Processing Standards) mode known-group validation when the client processes attacker-controlled DH-GEX group parameters. Successful exploitation leads to client-side process termination, resulting in a Denial of Service (DoS).

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
16%
KEV
Not listed

Published

June 23, 2026

Last Modified

July 8, 2026

Advisory Details (2)

Auto-updated Jun 23, 2026
Patch available. Sources: redhat.
redhat

2462351 – (CVE-2026-55653) CVE-2026-55653 openssh: Double free in Red Hat Enterprise Linux versions of OpenSSH DH-GEX client path during FIPS known-group validation leads to client-side denial of service

https://bugzilla.redhat.com/show_bug.cgi?id=2462351
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-55653

Vendor Advisories for CVE-2026-55653(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatopenssh-main-10.3p1-6.hum12026-07-08redhat

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.

Data Freshness Timeline

(refreshed 11× in last 7d / 80× 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. 2026-07-26 15:56 UTCEG score recompute
  2. 2026-07-26 15:56 UTCVendor advisory
  3. 2026-07-26 15:55 UTCGHSA enrichment
  4. 2026-07-26 14:54 UTCEPSS rescore
  5. 2026-07-25 14:18 UTCEPSS rescore
  6. 2026-07-24 14:18 UTCEPSS rescore
  7. 2026-07-23 14:18 UTCEPSS rescore
  8. 2026-07-23 03:20 UTCEG score recompute▲ 2.20
  9. 2026-07-22 14:08 UTCEPSS rescore
  10. 2026-07-21 15:25 UTCEPSS rescore
  11. 2026-07-20 17:08 UTCEPSS rescore
  12. 2026-07-19 14:31 UTCEPSS rescore
  13. 2026-07-19 14:31 UTCEPSS rescore
  14. 2026-07-19 02:29 UTCEPSS rescore
  15. 2026-07-18 10:04 UTCEPSS rescore
  16. 2026-07-17 05:29 UTCVendor advisory
  17. 2026-07-17 05:29 UTCGHSA enrichment
  18. 2026-07-16 17:03 UTCEPSS rescore
  19. 2026-07-16 07:18 UTCVendor advisory
  20. 2026-07-16 07:18 UTCGHSA enrichment
  21. 2026-07-15 16:57 UTCEPSS rescore
  22. 2026-07-15 16:57 UTCEPSS rescore
  23. 2026-07-15 09:06 UTCVendor advisory
  24. 2026-07-15 09:06 UTCGHSA enrichment
  25. 2026-07-15 02:00 UTCEPSS rescore
Show 67 more
  1. 2026-07-15 02:00 UTCEPSS rescore
  2. 2026-07-14 10:52 UTCVendor advisory
  3. 2026-07-14 10:52 UTCGHSA enrichment
  4. 2026-07-13 22:31 UTCEPSS rescore
  5. 2026-07-13 12:27 UTCVendor advisory
  6. 2026-07-13 12:27 UTCGHSA enrichment
  7. 2026-07-13 06:13 UTCEPSS rescore
  8. 2026-07-13 06:13 UTCEPSS rescore
  9. 2026-07-12 14:15 UTCVendor advisory
  10. 2026-07-12 14:15 UTCGHSA enrichment
  11. 2026-07-12 05:46 UTCEPSS rescore
  12. 2026-07-11 16:01 UTCVendor advisory
  13. 2026-07-11 16:01 UTCGHSA enrichment
  14. 2026-07-11 08:27 UTCEPSS rescore
  15. 2026-07-11 08:27 UTCEPSS rescore
  16. 2026-07-10 17:47 UTCVendor advisory
  17. 2026-07-10 17:47 UTCGHSA enrichment
  18. 2026-07-09 19:35 UTCVendor advisory
  19. 2026-07-09 19:35 UTCGHSA enrichment
  20. 2026-07-09 19:10 UTCEPSS rescore
  21. 2026-07-09 19:10 UTCEPSS rescore
  22. 2026-07-08 21:20 UTCGHSA enrichment
  23. 2026-07-08 15:16 UTCEPSS rescore
  24. 2026-07-08 15:16 UTCEPSS rescore
  25. 2026-07-08 14:36 UTCNVD updateCVSS v3 → 6.5
  26. 2026-07-08 14:05 UTCMITRE cvelistV5CVSS v3 → 4.3
  27. 2026-07-07 23:08 UTCGHSA enrichment
  28. 2026-07-07 13:46 UTCEPSS rescore
  29. 2026-07-07 13:46 UTCEPSS rescore
  30. 2026-07-07 00:57 UTCGHSA enrichment
  31. 2026-07-06 16:27 UTCEPSS rescore
  32. 2026-07-06 16:27 UTCEPSS rescore
  33. 2026-07-06 02:44 UTCGHSA enrichment
  34. 2026-07-06 02:23 UTCEPSS rescore
  35. 2026-07-06 02:23 UTCEPSS rescore
  36. 2026-07-05 04:32 UTCGHSA enrichment
  37. 2026-07-05 02:31 UTCEPSS rescore
  38. 2026-07-05 02:30 UTCEPSS rescore
  39. 2026-07-04 06:31 UTCEPSS rescore
  40. 2026-07-04 06:31 UTCEPSS rescore
  41. 2026-07-04 06:19 UTCGHSA enrichment
  42. 2026-07-03 08:04 UTCGHSA enrichment
  43. 2026-07-02 09:50 UTCGHSA enrichment
  44. 2026-07-01 15:07 UTCEPSS rescore
  45. 2026-07-01 11:39 UTCGHSA enrichment
  46. 2026-06-30 23:22 UTCEPSS rescore
  47. 2026-06-30 13:27 UTCGHSA enrichment
  48. 2026-06-29 15:10 UTCGHSA enrichment
  49. 2026-06-29 14:06 UTCEPSS rescore
  50. 2026-06-29 14:06 UTCEPSS rescore
  51. 2026-06-28 16:57 UTCGHSA enrichment
  52. 2026-06-28 14:07 UTCEPSS rescore
  53. 2026-06-28 04:56 UTCEPSS rescore
  54. 2026-06-28 04:56 UTCEPSS rescore
  55. 2026-06-27 18:45 UTCGHSA enrichment
  56. 2026-06-27 03:08 UTCEPSS rescore
  57. 2026-06-26 20:33 UTCGHSA enrichment
  58. 2026-06-25 22:22 UTCGHSA enrichment
  59. 2026-06-25 17:48 UTCNVD updateCVSS v3 → 6.5
  60. 2026-06-25 13:49 UTCEPSS rescore
  61. 2026-06-25 00:10 UTCGHSA enrichment
  62. 2026-06-24 14:05 UTCEPSS rescore
  63. 2026-06-24 01:59 UTCGHSA enrichment
  64. 2026-06-23 21:33 UTCEPSS rescore
  65. 2026-06-23 21:33 UTCEPSS rescore
  66. 2026-06-23 03:46 UTCEG score recompute
  67. 2026-06-23 03:45 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-55653?
CVE-2026-55653 is a medium vulnerability published on June 23, 2026. A flaw was found in OpenSSH. A malicious SSH server can exploit a double free vulnerability in the Diffie-Hellman Group Exchange (DH-GEX) client path. This occurs during FIPS (Federal Information Processing Standards) mode known-group validation when the client processes attacker-controlled DH-GEX…
When was CVE-2026-55653 disclosed?
CVE-2026-55653 was first published in the National Vulnerability Database on June 23, 2026, with the most recent update on July 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55653 actively exploited?
CVE-2026-55653 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 83.8% of all scored CVEs.
What is the CVSS score of CVE-2026-55653?
CVE-2026-55653 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-55653?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55653, 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-2026-55653

Explore →

Is Your Infrastructure Affected by CVE-2026-55653?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs