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CVE-2021-40539

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

CVSS 9.8 (CRITICAL) KEV: KNOWN CATALOG

Attention and evidence

HYPE SCORE
0.0/10
REALITY · THREAT PRIORITY
9.0/10
General review priority; not probability

Evidence confidence: Exploitation recorded

Why this priority?
  • Recorded exploitation baseline: +7.00
  • Technical severity: CVSS 9.8: +1.47
  • Fresh EPSS: 98.96%: +0.49

General review priority, not probability, victim count or asset-specific risk. A range covers missing CVSS/EPSS inputs within the current evidence state.

Sources: 12 documents and public datasets.

Hype components

Headline sample (25%)
0/100
Press, 30 days (60%)
0/100
Grounded branding (15%)
0/100
HYPE TOTAL0/100

Sources and documents

Microsoft
Press · 29 Jun 2023, 07:00 · Patch me if you can: Cyberattack Series - Microsoft
Check Point Research
Press · 12 Dec 2022, 08:00 · 12th December – Threat Intelligence Report - Check Point Research
The Record from Recorded Future News
Press · 15 Feb 2022, 08:00 · Red Cross blames hack on Zoho vulnerability, suspects APT attack - The Record from Recorded Future News
The Hacker News
Press · 03 Dec 2021, 08:00 · CISA Warns of Actively Exploited Critical Zoho ManageEngine ServiceDesk Vulnerability - The Hacker News
Palo Alto Networks
Press · 18 Nov 2021, 08:00 · Mapping Zoho ADSelfService Plus CVE-2021-40539 in the Wild - Palo Alto Networks
See all 12 source documents
Arctic Wolf
Press · 10 Nov 2021, 08:00 · CVE-2021- 40539 - Arctic Wolf
Tech Monitor
Press · 08 Nov 2021, 08:00 · Zoho hack: Here's what businesses need to know about the major breach - Tech Monitor
Microsoft
Press · 08 Nov 2021, 08:00 · Threat actor DEV-0322 exploiting ZOHO ManageEngine ADSelfService Plus - Microsoft
The Hacker News
Press · 08 Nov 2021, 08:00 · Experts Detail Malicious Code Dropped Using ManageEngine ADSelfService Exploit - The Hacker News
The Hacker News
Press · 09 Sep 2021, 07:00 · CISA Warns of Actively Exploited Zoho ManageEngine ADSelfService Vulnerability - The Hacker News
BleepingComputer
Press · 08 Sep 2021, 07:00 · Zoho patches actively exploited critical ADSelfService Plus bug - BleepingComputer
The Record from Recorded Future News
Press · 07 Sep 2021, 07:00 · CISA warns of Zoho server zero-day exploited in the wild - The Record from Recorded Future News

Score evolution

● Hype   ● Reality

Earlier evidence-support scores are retained in history; this chart shows only the current priority definition.

First record: hype 0.0 · reality 9.0 (2026-11-02 15:12). The curve appears once the score changes.

Public exploit evidence

1

Public exploit entries / repo candidates

See 1 repos with metrics
RepositoryStarsForksLanguageUpdated
DarkSprings/CVE-2021-4053921—17 Sep 2021, 02:56
Evidence context and dated references

Reality is general threat/review priority, combining observed exploitation, CVSS severity and fresh EPSS. Evidence confidence is separate. This is not calibrated risk, a victim count or an asset-specific assessment. A range reflects missing numeric inputs.

Evidence in context

Confidence in exploitation evidence
Exploitation recorded
Priority basis
Recorded exploitation; CVSS 9.8; EPSS 99.0%
Attention, last 30 days
0 distinct story titles; 0 press documents; 0 publisher domains.
Technical potential
network access, no prior privileges, no user interaction.
Observed activity
Exploitation recorded in CISA KEV.
Known scale
Not quantified.
Evidence confidence basis
Trusted exploitation confirmation

Score evaluated: 2026-11-05 13:58:30.019134+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z

Source event timeline
First press mention
07 Sep 2021, 07:00
Published
07 Sep 2021, 16:06
Added to the CISA KEV catalog
03 Nov 2021, 00:00
Latest press mention
29 Jun 2023, 07:00
Score calculated
05 Nov 2026, 13:58
PoCs on GitHub
1 repositories