CVE-2021-40539
Actively exploited. CVE-2021-40539 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.
Public exploit code is available. Proof-of-concept or working exploit code for CVE-2021-40539 is indexed in Metasploit, GitHub PoC and Nuclei. Expect opportunistic scanning and exploitation attempts — prioritize remediation.
Zoho ManageEngine ADSelfService Plus contains an authentication bypass vulnerability affecting the REST API URLs which allow for remote code execution.
CSIRTS triage
- What
- Zoho ManageEngine ADSelfService Plus contains an authentication bypass vulnerability affecting the REST API URLs, allowing for remote code execution.
- Who is affected
- Deployments of Zoho ManageEngine ADSelfService Plus are affected.
- Urgency
- Remediation is urgent due to active exploitation and critical severity.
- Action
- Update to the latest version of ManageEngine ADSelfService Plus.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch CVE-2021-40539
Get an email if CVE-2021-40539 is added to CISA KEV, gains public exploit code, or a new advisory cites it — max one per day, one-click unsubscribe.
Exploitation outlook
- Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 100% of all EPSS-scored CVEs.
Exploit availability
Public exploit or proof-of-concept code for CVE-2021-40539 is indexed in these free datasets. Available exploit code raises real-world risk independent of the CVSS score.
- MetasploitA Metasploit Framework module targets this CVE — weaponized, point-and-click exploitation.look it up ↗
- GitHub PoCPublic proof-of-concept repositories on GitHub reference this CVE.look it up ↗
- NucleiA nuclei-templates detection/PoC template exists for this CVE.look it up ↗
Advisory coverage (1)
- criticalexploitedCVE-2021-40539: Zoho ManageEngine ADSelfService Plus Authentication Bypass Vulnerabilitycisa-kev · 2021-11-03
External references
Embed the live status
— this badge updates automatically when the KEV or exploit status changes. How to embed it →
[](https://www.csirts.com/cve/CVE-2021-40539)