CVE-2026-21523

HIGHNVD 8.08.0—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.0 under NVD CVSS v3. EPSS exploit probability: 0.8%, top 47% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this week
8.0
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 8.0Exploit: NoneExposed: 0

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

Time-of-check time-of-use (toctou) race condition in GitHub Copilot and Visual Studio allows an authorized attacker to execute code over a network.

CVSS v3
8.0
EG Score
8.0(medium)
EG Risk
36(Track)
EG Risk 36/100SSVC: 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
Severity80% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
52.5%
KEV
Not listed

Published

February 10, 2026

Last Modified

February 11, 2026

Advisory Details (1)

Auto-updated Jun 10, 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-2026-21523

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

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

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Frequently asked(5)

What is CVE-2026-21523?
CVE-2026-21523 is a high vulnerability published on February 10, 2026. Time-of-check time-of-use (toctou) race condition in GitHub Copilot and Visual Studio allows an authorized attacker to execute code over a network.
When was CVE-2026-21523 disclosed?
CVE-2026-21523 was first published in the National Vulnerability Database on February 10, 2026, with the most recent update on February 11, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-21523 actively exploited?
CVE-2026-21523 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 52.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-21523?
CVE-2026-21523 has a CVSS v3 base score of 8.0 (NVD).
How do I remediate CVE-2026-21523?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-21523, 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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