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
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 6.5Exploit: None knownExposed services: Not assessed

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
6.5MEDIUMmedium confidence
EG Risk
29
EG Risk 29/100

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%
EPSS PROB
0.5%
EPSS %ILE
41st
KEV
Not listed

Published

June 23, 2026

Last Modified

September 1, 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(8)

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

Patch Availability(6)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatrhui5/rhua-tp-rhel9:17872412602026-08-24redhat
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 7× in last 7d / 29× 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 271 total refreshes for this CVE.

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

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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 on June 23, 2026, with the most recent update on September 1, 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 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-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?
A fix for CVE-2026-55653 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55653 are linked in the Vendor Advisories panel on this page.

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