CVE-2026-55653

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 78% 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
22%
KEV
Not listed

Published

June 23, 2026

Last Modified

August 18, 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(7)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatrhui5/rhua-rhel9:17865335292026-08-12redhat
redhatopenssh-0:9.9p1-25.el10_22026-07-30redhat
redhatopenssh-0:8.0p1-30.el8_102026-07-30redhat
redhatopenssh-0:9.9p1-9.el9_82026-07-29redhat
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 27× in last 7d / 114× 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.

Showing the most recent 100 of 197 total refreshes for this CVE.

  1. 2026-08-20 22:55 UTCEPSS rescore
  2. 2026-08-20 11:17 UTCEG score recompute
  3. 2026-08-20 11:17 UTCVendor advisory
  4. 2026-08-20 11:17 UTCGHSA enrichment
  5. 2026-08-19 17:04 UTCEPSS rescore
  6. 2026-08-19 13:06 UTCVendor advisory
  7. 2026-08-19 13:06 UTCGHSA enrichment
  8. 2026-08-18 14:54 UTCEG score recompute
  9. 2026-08-18 14:54 UTCVendor advisory
  10. 2026-08-18 14:54 UTCGHSA enrichment
  11. 2026-08-18 13:48 UTCEPSS rescore
  12. 2026-08-17 13:47 UTCEPSS rescore
  13. 2026-08-17 07:33 UTCEG score recompute
  14. 2026-08-17 07:33 UTCVendor advisory
  15. 2026-08-17 07:33 UTCGHSA enrichment
  16. 2026-08-16 14:56 UTCEPSS rescore
  17. 2026-08-16 09:22 UTCEG score recompute
  18. 2026-08-16 09:22 UTCVendor advisory
  19. 2026-08-16 09:22 UTCGHSA enrichment
  20. 2026-08-16 02:14 UTCEPSS rescore
  21. 2026-08-15 11:11 UTCEG score recompute
  22. 2026-08-15 11:11 UTCVendor advisory
  23. 2026-08-15 11:11 UTCGHSA enrichment
  24. 2026-08-15 01:30 UTCEPSS rescore
  25. 2026-08-14 12:59 UTCEG score recompute
Show 75 more
  1. 2026-08-14 12:59 UTCVendor advisory
  2. 2026-08-14 12:59 UTCGHSA enrichment
  3. 2026-08-13 22:00 UTCEPSS rescore
  4. 2026-08-13 14:47 UTCVendor advisory
  5. 2026-08-13 14:47 UTCGHSA enrichment
  6. 2026-08-12 16:36 UTCVendor advisory
  7. 2026-08-12 16:36 UTCGHSA enrichment
  8. 2026-08-12 16:04 UTCEG score recompute
  9. 2026-08-12 16:04 UTCVendor advisory
  10. 2026-08-12 16:04 UTCGHSA enrichment
  11. 2026-08-12 13:51 UTCEPSS rescore
  12. 2026-08-12 10:22 UTCEG score recompute
  13. 2026-08-12 10:22 UTCVendor advisory
  14. 2026-08-12 10:22 UTCGHSA enrichment
  15. 2026-08-11 12:10 UTCEG score recompute
  16. 2026-08-11 12:10 UTCVendor advisory
  17. 2026-08-11 12:10 UTCGHSA enrichment
  18. 2026-08-11 00:00 UTCEPSS rescore
  19. 2026-08-10 13:59 UTCVendor advisory
  20. 2026-08-10 13:59 UTCGHSA enrichment
  21. 2026-08-09 15:47 UTCEG score recompute
  22. 2026-08-09 15:47 UTCVendor advisory
  23. 2026-08-09 15:47 UTCGHSA enrichment
  24. 2026-08-09 13:46 UTCEPSS rescore
  25. 2026-08-08 17:36 UTCEG score recompute
  26. 2026-08-08 17:36 UTCVendor advisory
  27. 2026-08-08 17:36 UTCGHSA enrichment
  28. 2026-08-08 16:37 UTCEPSS rescore
  29. 2026-08-07 19:24 UTCEG score recompute
  30. 2026-08-07 19:24 UTCVendor advisory
  31. 2026-08-07 19:24 UTCGHSA enrichment
  32. 2026-08-06 21:12 UTCEG score recompute
  33. 2026-08-06 21:12 UTCVendor advisory
  34. 2026-08-06 21:12 UTCGHSA enrichment
  35. 2026-08-06 13:47 UTCEPSS rescore
  36. 2026-08-05 23:01 UTCEG score recompute
  37. 2026-08-05 23:01 UTCVendor advisory
  38. 2026-08-05 23:01 UTCGHSA enrichment
  39. 2026-08-05 19:17 UTCEPSS rescore
  40. 2026-08-05 00:49 UTCEG score recompute
  41. 2026-08-05 00:49 UTCVendor advisory
  42. 2026-08-05 00:49 UTCGHSA enrichment
  43. 2026-08-04 15:10 UTCEPSS rescore
  44. 2026-08-04 10:39 UTCEPSS rescore
  45. 2026-08-04 02:23 UTCEG score recompute
  46. 2026-08-04 02:23 UTCVendor advisory
  47. 2026-08-04 02:23 UTCGHSA enrichment
  48. 2026-08-03 10:36 UTCEPSS rescore
  49. 2026-08-03 04:11 UTCVendor advisory
  50. 2026-08-03 04:11 UTCGHSA enrichment
  51. 2026-08-02 05:58 UTCEG score recompute
  52. 2026-08-02 05:58 UTCVendor advisory
  53. 2026-08-02 05:58 UTCGHSA enrichment
  54. 2026-08-02 02:27 UTCEPSS rescore
  55. 2026-08-01 07:46 UTCEG score recompute
  56. 2026-08-01 07:46 UTCVendor advisory
  57. 2026-08-01 07:46 UTCGHSA enrichment
  58. 2026-08-01 04:16 UTCEPSS rescore
  59. 2026-07-31 07:48 UTCEG score recompute
  60. 2026-07-31 07:48 UTCVendor advisory
  61. 2026-07-31 07:48 UTCGHSA enrichment
  62. 2026-07-30 16:28 UTCEPSS rescore
  63. 2026-07-30 09:35 UTCEG score recompute
  64. 2026-07-30 09:35 UTCVendor advisory
  65. 2026-07-30 09:35 UTCGHSA enrichment
  66. 2026-07-30 09:02 UTCVendor advisory
  67. 2026-07-30 09:02 UTCGHSA enrichment
  68. 2026-07-30 06:39 UTCVendor advisory
  69. 2026-07-30 06:39 UTCGHSA enrichment
  70. 2026-07-30 02:40 UTCEG score recompute
  71. 2026-07-30 02:40 UTCVendor advisory
  72. 2026-07-30 02:40 UTCGHSA enrichment
  73. 2026-07-30 01:30 UTCEPSS rescore
  74. 2026-07-29 01:18 UTCEG score recompute
  75. 2026-07-29 01:18 UTCVendor advisory

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 August 18, 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 78.4% 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.

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