Zoho ManageEngine ADSelfService Plus Authentication Bypass Vulnerability
Zoho ManageEngine ADSelfService Plus contains an authentication bypass vulnerability affecting the REST API URLs which allow for remote code execution.
- Vendor
- Zoho
- Product
- ManageEngine
- CVSS
- 9.8
- EPSS (exploit probability)
- 99.0%
- Status
- kevransomware use
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2021-40539 being exploited?
Yes. CISA added CVE-2021-40539 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild. CISA marks it as known to be used in ransomware campaigns.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 99.0% (scored October 14, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-10-21. Full cross-catalog view: /kev-comparison
What to do
CISA required actionApply updates per vendor instructions.
US federal civilian agencies must remediate by (14 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Zoho ManageEngine CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2022-28810 Zoho ManageEngine ADSelfService Plus Remote Code Execution Vulnerability | [ MEDIUM ] | 6.8 | 71.0% | |
| CVE-2022-47966 Zoho ManageEngine Multiple Products Remote Code Execution Vulnerabilityransomware use | [ CRITICAL ] | 9.8 | 99.8% | |
| CVE-2022-35405 Zoho ManageEngine Multiple Products Remote Code Execution Vulnerability | [ CRITICAL ] | 9.8 | 99.9% | |
| CVE-2020-10189 Zoho ManageEngine Desktop Central File Upload Vulnerability | [ CRITICAL ] | 9.8 | 99.9% | |
| CVE-2019-8394 Zoho ManageEngine ServiceDesk Plus (SDP) File Upload Vulnerability | [ MEDIUM ] | 6.5 | 63.3% |