Background exploitation KEV catalog
CVE-2021-36742

Trend Micro Multiple Products Improper Input Validation Vulnerability

A 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 local attacker to escalate privileges on affected installations. Please note: an…

CheckOps priority index
4.4/10 Patch within 7 days
Severity7.8
Probability0.1
Exploitation2/5

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

EPSS · today 1.5% higher than 74.0% of CVEs
CVSS 3.1 7.8 AV:L/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

05010026 Sep05 Oct15 Oct24 Oct02 Nov
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 %1.5%
  • 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

A 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 local attacker to escalate privileges on affected installations. Please note: an attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

Affected products

Trend Micro OfficeScanTrend Micro Worry-Free Business SecurityTrend Micro Apex OneApex One, Apex One as a Service, and Worry-Free Business Security
Affected versions
  • XG SP1
  • 10.0 SP1
  • 2019, SaaS
Weaknesses (CWE)

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

  1. Published

  2. Exploitation reported (ENISA)

  3. Added to the KEV catalog

  4. 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-2021-36741Trend Micro Multiple Products Improper Input Validation Vulnerability
    4.9 · Background exploitation

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Sources: CISA KEV · ENISA EUVD · FIRST EPSS · OSV. Public data aggregated by CheckOps, updated automatically. Source texts remain the property of their authors. All exploited vulnerabilities