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CVE-2021-40539

Zoho ManageEngine ADSelfService Plus Authentication Bypass

9.8 CRITICALActively exploited (CISA KEV)Used in ransomwarePublic exploitEPSS 99.0%
  1. Published7 Sept 2021
  2. Added to CISA KEV3 Nov 2021
  3. Remediation due17 Nov 2021
Actively exploited (CISA KEV)

Zoho ManageEngine ADSelfService Plus contains an authentication bypass vulnerability affecting the REST API URLs which allow for remote code execution.

Added to KEV: 3 Nov 2021Federal remediation due: 17 Nov 2021Used in ransomware

Description

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

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Zohocorp Manageengine Adselfservice Plus< 6.1 · 6.1

Remediation

Fixed in
Zohocorp Manageengine Adselfservice Plus≥ 6.1

References

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Frequently asked

Is CVE-2021-40539 being actively exploited?

Yes. CVE-2021-40539 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 3 Nov 2021. It has been used in ransomware campaigns.

How severe is CVE-2021-40539?

CVE-2021-40539 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 99.0% probability of exploitation.

Which products are affected by CVE-2021-40539?

Affected products include Zohocorp Manageengine Adselfservice Plus.

How do I fix CVE-2021-40539?

Upgrade affected software to a fixed version, for example Zohocorp Manageengine Adselfservice Plus 6.1 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2021-40539 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.