Exploited CVEs / Trend Micro / CVE-2021-36741

CVE-2021-36741

Trend Micro Multiple Products Improper Input Validation Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2021-11-17 (that deadline has passed); treat that date as the outer bound for your own environment. Check the vendor security advisory for the fix.

Risk summary

HighCISA KEV

8.8

CVSS base

5.0%

EPSS exploit probability

High

Severity

2021-11-03

Added to KEV

2021-11-17 (past due)

CISA due date

Actively exploited Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security vulnerability, High severity, CVSS 8.8. Added to the CISA KEV catalog 2021-11-03.

Senserva AI read on CVE-2021-36741 CISA required action Official fix for CVE-2021-36741 Admin questions

Senserva AI Opinion for CVE-2021-36741

A remote attacker can upload files to systems running vulnerable Trend Micro Apex One, Apex One as a Service, or Worry-Free Business Security through this improper input validation flaw, CVSS 8.8 and confirmed exploited. Arbitrary file upload against an endpoint security product is a short step from compromise of the machines it manages. Organizations running these agents unpatched since 2021 should treat the exposure as fleet-wide.

Do this: Patch Trend Micro management servers and agents for CVE-2021-36741 and check for unexpected uploaded files.

AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2021-36741

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I run IT security. Facts for CVE-2021-36741, an actively exploited vulnerability (source: https://senserva.com/cve/CVE-2021-36741.html, data from CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2021-36741: Trend Micro Multiple Products Improper Input Validation Vulnerability
- Affected: Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security
- Severity: High, CVSS 8.8; EPSS 30-day exploitation probability 5.0%
- Added to CISA KEV: 2021-11-03; federal remediation due 2021-11-17
- Ransomware-linked: no
- CISA required action: Apply updates per vendor instructions.
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) The fastest safe path to remediation. 4) How to check whether my environment is exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Patch now

Exploited in the wild: confirmed by the CISA KEV catalog, not predicted.

No vendor fix is mapped yet. This page refreshes daily and will name the patch the day one is published.

Do this now: Federal remediation deadline 2021-11-17; treat it as your outer bound. Patch now and verify deployment on every exposed device.

Updated August 14, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Full tracking and change history for CVE-2021-36741

Published: 2021-11-03
Last revised: 2021-11-03
Changes tracked: 1

Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.

Senserva Watchevery change we have recorded for this one

What changed, and when

2021-11-03 added to the CISA KEV catalog by CISA
2026-07-17 CVSS 0.0 to 8.8; EPSS first scored at 5.0%

Recorded by Senserva on the dates shown, from CISA KEV and FIRST EPSS. This is what moved and when, which neither the vendor advisory nor NVD publishes.

CISA required action

Federal (BOD 22-01) remediation due date: 2021-11-17 (past due).

Apply updates per vendor instructions.

Official fix for CVE-2021-36741

Check the vendor's security advisory channel for the patched Apex One, Apex One as a Service, and Worry-Free Business Security versions and workarounds.

CISA KEV entry

Common questions about CVE-2021-36741

Is CVE-2021-36741 actively exploited?

Yes. CVE-2021-36741 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2021-11-03, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 5.0%.

What is the CISA deadline and required action for CVE-2021-36741?

CISA set the federal (BOD 22-01) remediation due date at 2021-11-17, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply updates per vendor instructions.

What fixes CVE-2021-36741?

Check the vendor's security advisory for the patched Apex One, Apex One as a Service, and Worry-Free Business Security versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.

Can I ask my own AI about CVE-2021-36741?

Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2021-36741's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).

Scope and sources

More exploited Trend Micro CVEs: CVE-2026-34926 CVE-2025-54948 CVE-2023-41179 CVE-2022-40139 CVE-2022-26871 CVE-2019-18187 CVE-2020-8599 CVE-2020-8467
All Trend Micro exploited CVEs on one page: Trend Micro vulnerabilities actively exploited.
Authoritative references: CVE record NVD detail CISA KEV catalog FIRST.org EPSS

Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.