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Exploited vulnerability · CISA KEV

Is CVE-2021-40539 exploited? Yes: in CISA KEV since 3 Nov 2021

Gociux · Zoho ManageEngine · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2021-40539, Zoho ManageEngine ADSelfService Plus Authentication Bypass Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 3 Nov 2021, 57 days after it was published. It is known to be used in ransomware campaigns. It affects Zoho ManageEngine. If you run it, CISA's required action is: Apply updates per vendor instructions.

exploitedYesCISA KEV · 3 Nov 2021
ransomwareKnownused in campaigns
EPSStop 1%among the most likely CVEs to be exploited
severity9.8CVSS 3.1 · critical
US federal due17 Nov 2021BOD 22-01 deadline

What it is

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

VendorZoho (9 exploited CVEs in KEV)
ProductManageEngine
VulnerabilityZoho ManageEngine ADSelfService Plus Authentication Bypass Vulnerability
WeaknessCWE-55
Published7 Sep 2021
Added to KEV3 Nov 2021
Reported by (CNA)mitre

What to do

  1. Check whether you run it. Look for ManageEngine in your asset inventory, including appliances and cloud images. Stack check lists every exploited Zoho CVE at once.
  2. Apply the fix. Apply updates per vendor instructions.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 7 Sep 2021.
  4. Get told next time. Email alerts when CISA adds a CVE for Zoho.

Other exploited CVEs in ManageEngine

References

Questions

Is CVE-2021-40539 being exploited?

Yes. CISA added CVE-2021-40539 to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, which means there is reliable evidence of exploitation in the wild.

Is CVE-2021-40539 used in ransomware attacks?

Yes, CISA lists it as known to be used in ransomware campaigns.

How do I fix CVE-2021-40539?

Apply updates per vendor instructions. Check Zoho's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected ManageEngine and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in November 2021 · Zoho scorecard · act-now radar.

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