CVE-2026-56191

CRITICALPre-NVD 10.010.0—
EchelonGraph scoreHIGH confidence

Score 10.0 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-24. the CNA's CVSS baseline 10.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:microsoft, epss, ghsa
Trending — 4 sources updated this week
10.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 10.0Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.

CVSS v3
10.0
EG Score
10.0(high)
EG Risk
60(Track)
EG Risk 60/100SSVC: 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
Severity100% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
48%
KEV
Not listed

Published

July 24, 2026

Last Modified

July 30, 2026

Advisory Details (1)

Auto-updated Jul 30, 2026
Patch available. Sources: microsoft.
microsoft Patch Available

Security Update Guide - Microsoft Security Response Center

Security Update Guide - Microsoft Security Response Center. Patch available via Microsoft Security Update

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56191

Vendor Advisories for CVE-2026-56191(2)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 97× in last 7d / 101× 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 101 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-56191?
CVE-2026-56191 is a critical vulnerability published on July 24, 2026. Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.
When was CVE-2026-56191 disclosed?
CVE-2026-56191 was first published in the National Vulnerability Database on July 24, 2026, with the most recent update on July 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-56191 actively exploited?
CVE-2026-56191 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 51.8% of all scored CVEs.
What is the CVSS score of CVE-2026-56191?
CVE-2026-56191 has a CVSS v4.0 base score of 10.0 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-56191?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56191, 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

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