CVE-2021-36741: Trend Micro Multiple Products Improper Input Validation Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, 97 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 5%
EPSS score, percentile 92.1 of all scored records
- How severe?
- 8.8 High
CVSS v3.1 base score, from CISA's enrichment of the record
- What should I do?
CISA deadline 17 Nov 2021. Apply updates per vendor instructions.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- 2019, SaaS
- XG SP1
- 10.0 SP1
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Apply updates per vendor instructions.
CISA due date for this action: 17 November 2021.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
- https://success.trendmicro.com/dcx/s/solution/000287819?language=en_US
- https://success.trendmicro.com/dcx/s/solution/000287820?language=en_US
- https://nvd.nist.gov/vuln/detail/CVE-2021-36741
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 2019, SaaS |
| Status | Versions |
|---|---|
| Affected | XG SP1 |
| Status | Versions |
|---|---|
| Affected | 10.0 SP1 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security contain an improper input validation vulnerability that allows a remote attacker to upload files.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2021-36741 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Nov 2021.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 17 Nov 2021.
- The CVE record was published on 29 Jul 2021, 97 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 8.8 (High), taken from CISA's enrichment of the record.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 5% (percentile 92.1), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 29 Jul 2021 | CVE record published |
| 3 Nov 2021 | Added to CISA KEV |
| 17 Nov 2021 | CISA due date for the required action |
| 21 Oct 2025 | CVE record last updated |
References
More exploited Trend Micro vulnerabilities
- CVE-2026-34926: Trend Micro Apex One (On-Premise) Directory Traversal Vulnerability
- CVE-2025-54948: Trend Micro Apex One OS Command Injection Vulnerability
- CVE-2023-41179: Trend Micro Apex One and Worry-Free Business Security Remote Code Execution Vulnerability
- CVE-2022-40139: Trend Micro Apex One and Apex One as a Service Improper Validation Vulnerability
- CVE-2022-26871: Trend Micro Apex Central Arbitrary File Upload Vulnerability
- CVE-2019-18187: Trend Micro OfficeScan Directory Traversal Vulnerability