CVE-2021-36741
HighExploitedPublic exploitAn 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.
Published Jul 29, 2021 · Updated Oct 31, 2025
Key Facts
Patch immediately- CVE-2021-36741 is a high-severity vulnerability (CVSS 8.8 v3.1) affecting Apex One (Trendmicro), Officescan Business Security (Trendmicro), Officescan (Trendmicro) and 4 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Aug 11, 2021. Public exploit code is available.
- EPSS estimates a 5.0% probability of exploitation in the next 30 days.
- No fixed version is listed yet; check the vendor advisory for mitigations.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
8.8
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
5.0%
Higher than 92.0% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
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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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | Nov 17, 2021 | Not reported |
| Industry KEV feed | Aug 11, 2021 | Nov 17, 2021 | Not reported |
| CIRCL KEV | Nov 3, 2021 | Nov 17, 2021 | Not reported |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
7 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Apex OneTrendmicro | 2019 | n/a |
| Officescan Business SecurityTrendmicro | 10.0-sp1 | n/a |
| OfficescanTrendmicro | xg-sp1 | n/a |
| Worry-Free Business SecurityTrendmicro | 10.0-sp1 | n/a |
| Trend Micro Apex One | >= 2019, SaaS | n/a |
Timeline
Publicly disclosed
Jul 29, 2021
Added to Industry KEV feed
Aug 11, 2021
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Oct 31, 2025
Weakness Type
- CWE-434 Unrestricted Upload of File with Dangerous Type
References
- advisoryhttps://success.trendmicro.com/jp/solution/000287796
- advisoryhttps://success.trendmicro.com/jp/solution/000287815
- advisoryhttps://success.trendmicro.com/solution/000287819
- advisoryhttps://success.trendmicro.com/solution/000287820
- exploitVulnCheck exploitation report
FAQ
Common Questions.
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.
Affected: Apex One (Trendmicro) versions 2019; Officescan Business Security (Trendmicro) versions 10.0-sp1; Officescan (Trendmicro) versions xg-sp1, among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Aug 11, 2021.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of Nov 17, 2021.
Public exploit code is available.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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