CVE-2026-21537

HIGHNVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-02-10. NVD baseline CVSS 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 8.8Exploit: None knownExposed: 0

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

Improper control of generation of code ('code injection') in Microsoft Defender for Linux allows an unauthorized attacker to execute code over an adjacent network.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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
Severity88% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
43%
KEV
Not listed

Published

February 10, 2026

Last Modified

August 19, 2026

Advisory Details (1)

Auto-updated Jun 7, 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-2026-21537

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 7× in last 7d / 52× 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 159 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2026-21537?
CVE-2026-21537 is a high vulnerability published on February 10, 2026. Improper control of generation of code ('code injection') in Microsoft Defender for Linux allows an unauthorized attacker to execute code over an adjacent network.
When was CVE-2026-21537 disclosed?
CVE-2026-21537 was first published in the National Vulnerability Database on February 10, 2026, with the most recent update on August 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-21537 actively exploited?
CVE-2026-21537 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 57.1% of all scored CVEs.
What is the CVSS score of CVE-2026-21537?
CVE-2026-21537 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-21537?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-21537, 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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