Background exploitation KEV catalog

CVE-2021-36741

Trend Micro Multiple Products Improper Input Validation Vulnerability

CheckOps priority index

4.9/10 Patch within 7 days

Severity8.8

Probability0.5

Exploitation2/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 5.0% higher than 92.2% of CVEs

CVSS 3.1 8.8 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:

Exploited for 1,826 days 03 Nov 2021

CISA due date 17 Nov 2021 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 2 / 5

KEV catalog (CISA)03 Nov 2021
Exploited in EUVD (ENISA)03 Nov 2021
Used by ransomwareno
EPSS above 10 %5.0%
No account, over the networkno

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

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

Trend Micro Worry-Free Business SecurityTrend Micro Apex OneTrend Micro OfficeScanApex One, Apex One as a Service, and Worry-Free Business Security

Affected versions

10.0 SP1
2019, SaaS
XG SP1

Weaknesses (CWE)

CWE-22

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

29 Jul 2021
Published
03 Nov 2021
Exploitation reported (ENISA)
03 Nov 2021
Added to the KEV catalog
17 Nov 2021
CISA remediation due date

References

Other exploited vulnerabilities from the same vendor

CVE-2026-34926Trend Micro Apex One (On-Premise) Directory Traversal Vulnerability
4.9 · Actively exploited
CVE-2025-54948Trend Micro Apex One OS Command Injection Vulnerability
6.9 · Background exploitation
CVE-2023-41179Trend Micro Apex One and Worry-Free Business Security Remote Code Execution Vulnerability
4.2 · Background exploitation
CVE-2022-40139Trend Micro Apex One and Apex One as a Service Improper Validation Vulnerability
4.2 · Background exploitation
CVE-2022-26871Trend Micro Apex Central Arbitrary File Upload Vulnerability
6.9 · Background exploitation
CVE-2021-36742Trend Micro Multiple Products Improper Input Validation Vulnerability
4.4 · Background exploitation