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
9.8EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 99%CVSS: 9.8Exploit: cisa kev · ssvc active · kev ransomware · Metasploit · epss top5pct · epss high · public exploitExposed: 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)
EG Risk
99(Act)
EG Risk 99/100SSVC: Act

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
Severity98% × 45%
Exploitation100% × 40%
Automatability100% × 15%
Action: Fix now — active exploitation, automatable, high impact.
EPSS PROB
99%
EPSS %ILE
100%
KEV
⚠ Exploited

Published

September 7, 2021

Last Modified

November 5, 2025

Advisory Details (4)

Auto-updated Sep 3, 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

Locked Out | 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 52× in last 7d / 219× 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 702 total refreshes for this CVE.

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

Explore →

Is Your Infrastructure Affected by CVE-2021-40539?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs