What is the CVSS score of CVE-2021-36741?

CVE-2021-36741 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 5.0%.

Is CVE-2021-36741 being actively exploited?

Yes, CVE-2021-36741 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, confirming active in-the-wild exploitation. Immediate patching is required.

Trend Micro CVE-2021-36741

HIGH

Unrestricted Upload of File with Dangerous Type (CWE-434)

2021-07-29 security@trendmicro.com

Trend Micro File Upload Apex One Worry Free Business Security Officescan Officescan Business Security

8.8

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-434 OWASP Top 10:2025 A06:2025 - Insecure Design ASVS 5.0 V5 - File Handling File type validation, storage isolation MITRE ATT&CK 2 techniques across 2 tactics: Command and Control, Persistence The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 8.8 (HIGH). Attack characteristics: network attack vector, low complexity, low privileges required, no user interaction not required.
Exploit ScenarioDerived	A remote attacker could upload malicious files that can be executed on the server by sending crafted requests to the affected application.

This Week Schedule remediation this week. Why: Active threat signals + CRITICAL/HIGH severity.

Exploited in the wild (CISA KEV) No patch listed yet 5.0% exploitation probability (EPSS)

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AnalysisAI

An improper input validation vulnerability in Trend Micro Apex One, Apex One as a Service, OfficeScan XG, and Worry-Free Business Security 10.0 SP1 allows a remote attached to upload arbitrary files. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Validate file types server-side, store uploads outside webroot, use random filenames, scan for malware.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Unrestricted File Upload (CWE-434), which allows attackers to upload malicious files that can be executed on the server. An improper input validation vulnerability in Trend Micro Apex One, Apex One as a Service, OfficeScan XG, and Worry-Free Business Security 10.0 SP1 allows a remote attached to upload arbitrary files on affected installations. Please note: an attacker must first obtain the ability to logon to the product�s management console in order to exploit this vulnerability. Affected products include: Trendmicro Officescan, Trendmicro Officescan Business Security, Trendmicro Apex One, Trendmicro Worry-Free Business Security.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH

AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Added to CISA KEV

Jul 14, 2026 - 04:22 CISA

CVE Published

Jul 29, 2021 - 20:15 nvd

HIGH 8.8

DescriptionNVD

An improper input validation vulnerability in Trend Micro Apex One, Apex One as a Service, OfficeScan XG, and Worry-Free Business Security 10.0 SP1 allows a remote attached to upload arbitrary files on affected installations. Please note: an attacker must first obtain the ability to logon to the product�s management console in order to exploit this vulnerability.

Threat Intelligence Overview

EPSS Score

5.0%

Top 9% exploitable

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

CISA KEV

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV Yes

Public POC No

EPSS 5.0%

Patch available No

Active threat Yes

Deciding rule

Active threat signals + CRITICAL/HIGH severity

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Out-of-Cycle

Exploitation· derived

Active

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

High

Priority Score

Low Medium High Critical

KEV: +50

EPSS: +5

CVSS: +44

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Malicious File Upload HIGH

Malicious file upload attacks exploit insufficient validation when web applications accept user-provided files.

Affected Products (CPE)NVD

cpe:2.3:a:trendmicro:officescan:xg:sp1:*:*:*:*:*:*

cpe:2.3:a:trendmicro:officescan_business_security:10.0:sp1:*:*:*:*:*:*

cpe:2.3:a:trendmicro:apex_one:2019:*:*:*:*:*:*:*

cpe:2.3:a:trendmicro:worry-free_business_security:10.0:sp1:*:*:*:*:*:*

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References

Advisories & patches

ADVISORY https://success.trendmicro.com/jp/solution/000287796 ADVISORY https://success.trendmicro.com/jp/solution/000287815 ADVISORY https://success.trendmicro.com/solution/000287819 ADVISORY https://success.trendmicro.com/solution/000287820 REF https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36741

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