CVE-2026-40421

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreMEDIUM confidence

Score 4.3 from GitHub Security Advisory published 2026-05-12. the CNA's CVSS baseline 4.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:microsoft, epss, ghsa
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 4.3Exploit: None knownExposed services: Not assessed

A fix is referenced (a reference tagged "Patch", often a source commit), but no release containing it is confirmed — find the release that contains it; until it is applied, mitigate (WAF / firewall / segmentation).

Files or directories accessible to external parties in Microsoft Office Word allows an unauthorized attacker to disclose information locally.

CVSS v3
4.3
EG Score
4.3MEDIUMmedium confidence
EG Risk
20
EG Risk 20/100

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
Severity43% × 45%
Exploitation1% × 40%
Automatability0% × 15%
EPSS PROB
0.7%
EPSS %ILE
51st
KEV
Not listed

Published

May 12, 2026

Last Modified

August 10, 2026

Advisory Details (1)

Auto-updated May 16, 2026
Fix referenced — no release confirmed yet. Sources: microsoft.
microsoftMentions a patch (unverified)

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-2026-40421

Vendor Advisories for CVE-2026-40421(1)

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 6× in last 7d / 23× 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 244 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-40421?
CVE-2026-40421 is a medium vulnerability published on May 12, 2026. Files or directories accessible to external parties in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
When was CVE-2026-40421 disclosed?
CVE-2026-40421 was first published on May 12, 2026, with the most recent update on August 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40421 actively exploited?
CVE-2026-40421 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (51st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-40421?
CVE-2026-40421 has a CVSS base score of 4.3 (the CNA's own assessment, by microsoft; NVD's own analysis pending).
How do I remediate CVE-2026-40421?
A fix for CVE-2026-40421 is referenced (a reference tagged "Patch", often a source commit), but EchelonGraph has no release containing it on record. Check that reference and the vendor's advisory for a release that contains the fix and update to it; until then, restrict network exposure of the affected system or apply the vendor's mitigation. The vendor advisories EchelonGraph has for CVE-2026-40421 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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