BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2021
CVE-2021-36741High confidence

Trend Micro Multiple Products Improper Input Validation Vulnerability

Trend Micro · Apex One, Apex One as a Service, and Worry-Free Business Security

8.8HighCVSS 3.1
Recommended action
Mitigate now

CISA confirms exploitation in the wild and lists 2021-11-17 as the remediation due date.

Mitigation available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Critical, raised one band.upgradedsince 3 Nov 2021

Evidence used

  • CISA confirms exploitation in the wild.
  • EPSS is 4.95% for the current model date.

Compensating controls

  • Apply the linked authoritative mitigation while planning the permanent fix.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-23331

CISA KEV mirrored by ENISA

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.

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 3 Nov 2021. Evidence sources: cisa_kev.
ENISA score
8.8 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionMitigate now

CISA confirms exploitation in the wild and lists 2021-11-17 as the remediation due date.

Mitigation available
01

What, why and how

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.

What

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.

Why

The upload path does not sufficiently restrict the type, name, location or later execution of attacker-supplied files.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

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.

Why

The upload path does not sufficiently restrict the type, name, location or later execution of attacker-supplied files.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Confirmed in the wild

CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2021-11-03.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Unrestricted Upload of File with Dangerous Type → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-434 ↗

CWE-434: Unrestricted Upload of File with Dangerous Type. The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkCWE-434CISA KEV
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2021-23331Known-exploited evidence recorded

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.

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20210804Security Bulletin 04 Aug 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 04 Aug 2021, published on 4 August 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-582Multiples vulnérabilités dans les produits Trend Micro

De multiples vulnérabilités ont été découvertes dans les produits Trend Micro. Elles permettent à un attaquant de provoquer un contournement de la politique de sécurité, une atteinte à l'intégrité des données et une élévation de privilèges.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-002077複数のトレンドマイクロ製企業向けエンドポイントセキュリティ製品における複数の脆弱性

トレンドマイクロ株式会社が提供する複数の企業向けエンドポイントセキュリティ製品には、次の複数の脆弱性が存在します。 　* 不適切なパーミッションの割り当て (CWE-732) - CVE-2021-32464 　* パーミッションの不適切な保持 (CWE-281) - CVE-2021-32465 　* 不適切な入力確認 (CWE-20) - CVE-2021-36741 　* 不適切な入力確認 (CWE-20) - CVE-2021-36742 なお、開発者によると、CVE-2021-36741 および CVE-2021-36742 は、本脆弱性を悪用した攻撃が確認されているとのことです。 　 この脆弱性情報は、製品利用者への周知を目的に、開発者が JPCERT/CC に報告し、JPCERT/CC が開発者との調整を行いました。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Mitigation available
Affected
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
[パッチを適用する] 開発者が提供する情報をもとにパッチを適用してください。 開発者は本脆弱性の対策として次のパッチをリリースしています。 　* Apex One 2019 CP 9601 　* ウイルスバスターコーポレートエディション XG SP1 CP 6058 　* ウイルスバスタービジネスセキュリティ 10 SP1 Patch 2329 　* ウイルスバスタービジネスセキュリティサービス 6.7.1538 / 14.2.1295 以降 　 開発者によると、Apex One SaaS は 2021年7月21日のメンテナンスで修正済みとのことです。 [ワークアラウンドを実施する] 次の回避策を適用することで、本脆弱性の影響を軽減することが可能です。 　* 当該製品へのアクセスを、信頼できるネットワークからのみに制限する
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 29 Jul 2021 · Last source change 21 Oct 2025, 23:25 UTC · CWE-434 · Unrestricted Upload of File with Dangerous Type

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-23331
Product sourceCISA KEV
Remediation sourceCVE/CNA references
CWE sourceCISA ADP
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: removed remediation: jvndb.jvn.jp/JVNDB-2021-002077.html.
    Before
    remediation: jvndb.jvn.jp/JVNDB-2021-002077.html · vendor advisory: success.trendmicro.com/000287796 · vendor advisory: success.trendmicro.com/000287815 · 2 more references
    After
    vendor advisory: success.trendmicro.com/000287796 · vendor advisory: success.trendmicro.com/000287815 · vendor advisory: success.trendmicro.com/000287819 · 1 more references
    success.trendmicro.com ↗
  2. Remediation statusRemediation status changed from Mitigation available to Awaiting fix.
    Before
    Mitigation available
    After
    Awaiting fix
    success.trendmicro.com ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    2019, SaaS; XG SP1; 10.0 SP1 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    Trend Micro Apex One: 2019, SaaS; Trend Micro OfficeScan: XG SP1; Trend Micro Worry-Free Business Security: 10.0 SP1 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  4. Remediation statusRemediation status changed from Awaiting fix to Mitigation available.
    Before
    Awaiting fix
    After
    Mitigation available
    JVN iPedia ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Added to CISA KEV
Remediation guidance recorded
ENISA EUVD · EUVD-2021-23331↗JVN iPedia remediation guidance↗CISA KEV record↗CVE authority or vendor reference↗Vendor advisory↗Vendor advisory↗Vendor advisory↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-36741 · cve.blacktree.nl