CVE-2021-40539

CRITICALNVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 9.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 4 sources updated this weekExploited in the wild
9.8
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS: 99%CVSS: 9.8Exploit: NoneExposed: 0

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

Zoho ManageEngine ADSelfService Plus version 6113 and prior is vulnerable to REST API authentication bypass with resultant remote code execution.

CVSS v3
9.8
EG Score
9.8(high)
EPSS
99.9%
KEV
⚠ Exploited

Published

September 7, 2021

Last Modified

November 5, 2025

Advisory Details (4)

Auto-updated Jun 1, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: cisa.
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40539
generic

CVE-2021-40539: Authentication Bypass | ADSelfService Plus

https://www.manageengine.com/products/self-service-password/kb/how-to-fix-authentication-bypass-vulnerability-in-REST-API.html
generic

ManageEngine: ITOps, cybersecurity & service management software

https://www.manageengine.com
generic

Packet Storm

http://packetstormsecurity.com/files/165085/ManageEngine-ADSelfService-Plus-Authentication-Bypass-Code-Execution.html

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 51× in last 7d / 210× 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 377 total refreshes for this CVE.

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

Publicly available exploits

(5 references)

Working exploit code is in the public domain (1 Metasploit module) (3 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCBu0uCat/ADSelfService-Plus-RCE-CVE-2021-40539
    First seen Oct 16, 2024

    ADSelfService Plus RCE漏洞 检测工具 (二开)

    Open source ↗
  • GitHub PoCsynacktiv/CVE-2021-40539
    First seen Nov 3, 2021

    Exploitation code for CVE-2021-40539

    Open source ↗
  • GitHub PoCDarkSprings/CVE-2021-40539
    First seen Sep 17, 2021

    CVE-2021-40539 POC

    Open source ↗
  • Metasploitexploit/windows/http/manageengine_adselfservice_plus_cve_2021_40539✓ verified
    First seen Sep 7, 2021

    ManageEngine ADSelfService Plus CVE-2021-40539

    Open source ↗
  • Nucleihttp/cves/2021/CVE-2021-40539.yaml
    First seen Jan 1, 2021

    Zoho ManageEngine ADSelfService Plus v6113 - Unauthenticated Remote Command Execution

    Open source ↗

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2021-40539?
CVE-2021-40539 is a critical vulnerability published on September 7, 2021. Zoho ManageEngine ADSelfService Plus version 6113 and prior is vulnerable to REST API authentication bypass with resultant remote code execution.
When was CVE-2021-40539 disclosed?
CVE-2021-40539 was first published in the National Vulnerability Database on September 7, 2021, with the most recent update on November 5, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-40539 actively exploited?
Yes. CISA added CVE-2021-40539 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Zoho ManageEngine. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-40539?
CVE-2021-40539 has a CVSS v3 base score of 9.8 (NVD).
Which products are affected by CVE-2021-40539?
CVE-2021-40539 affects Zoho ManageEngine. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2021-40539?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-40539, 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

Explore the affected products and dependency analysis for CVE-2021-40539

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