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Full vulnerability report · 2024
CVE-2024-21413High confidence

Microsoft Outlook Improper Input Validation Vulnerability

Microsoft · Office Outlook

9.8CriticalCVSS 3.1
Recommended action
Patch now

CISA confirms exploitation in the wild and lists 2025-02-27 as the remediation due date.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, unchanged from published severity.unchanged

Evidence used

  • CISA confirms exploitation in the wild.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 94.66% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • 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 Microsoft Office Outlook and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  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-2024-19122

CISA KEV mirrored by ENISA

Microsoft Outlook Remote Code Execution Vulnerability

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 6 Feb 2025. Evidence sources: cisa_kev.
ENISA score
9.8 · CVSS 3.1
Advisory evidence
2 linked advisory records
Recommended actionPatch now

CISA confirms exploitation in the wild and lists 2025-02-27 as the remediation due date.

Patch available
01

What, why and how

Microsoft Outlook contains an improper input validation vulnerability that allows for remote code execution. Successful exploitation of this vulnerability would allow an attacker to bypass the Office Protected View and open in editing mode rather than protected mode.

What

Microsoft Outlook contains an improper input validation vulnerability that allows for remote code execution. Successful exploitation of this vulnerability would allow an attacker to bypass the Office Protected View and open in editing mode rather than protected mode.

Why

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

What

Microsoft Outlook contains an improper input validation vulnerability that allows for remote code execution. Successful exploitation of this vulnerability would allow an attacker to bypass the Office Protected View and open in editing mode rather than protected mode.

Why

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

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 2025-02-06.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Improper Input Validation → execute code or commands in the affected security context
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
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-20 ↗

CWE-20: Improper Input Validation. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

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:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

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.PRNonePrivileges required: The attacker does not need an account or existing 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
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
NetworkUnauthenticatedRemote code executionCWE-20CISA KEVPublic exploit reference
A

Official authority intelligence

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

ENISA EUVD · EUVD-2024-19122Known-exploited evidence recorded

Microsoft Outlook Remote Code Execution Vulnerability

Official EUVD record ↗
BSI · German · WID-SEC-2024-0389Microsoft Office: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in verschiedenen Microsoft Office Anwendungen ausnutzen, um beliebigen Code auszuführen, seine Privilegien zu eskalieren oder vertrauliche Informationen offenzulegen.

Official advisory ↗
Canadian Centre for Cyber Security · English · AV24-701Microsoft security advisory – December 2024 monthly rollup (AV24–701)

On December 10, 2024, Microsoft published security advisories to address vulnerabilities in multiple products. Included were updates for the following products: Microsoft has indicated that CVE-2024-49138 and CVE-2023-44487* have been exploited.

Official advisory ↗
Canadian Centre for Cyber Security · English · AV24-084Microsoft security advisory – February 2024 monthly rollup (AV24-084)

On February 13, 2024, Microsoft published security updates to address vulnerabilities in multiple products. Included were critical updates for the following products: Microsoft has indicated that CVE-2024-21413, CVE-2024-21412, CVE-2024-21410 and CVE-2024-21351 have been exploited.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20240214Security Bulletin 14 Feb 2024

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 14 Feb 2024, published on 14 February 2024. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0127Multiples vulnérabilités dans Microsoft Office

De multiples vulnérabilités ont été corrigées dans Microsoft Office . Elles permettent à un attaquant de provoquer une élévation de privilèges et une exécution de code arbitraire à distance.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2024-002843マイクロソフトの Microsoft 365 Apps および Office におけるリモートでコードを実行される脆弱性

マイクロソフトの Microsoft 365 Apps および Office には、Microsoft Outlook に不備があるため、リモートでコードを実行される脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-6102MS 2월 보안 위협에 따른 정기 보안 업데이트 권고

긴급 | 원격 코드 실행 | | Microsoft Exchange Server | 긴급 | 권한 상승 | | Microsoft .NET | 중요 | 서비스 거부 | | Microsoft Visual Studio | 중요 | 서비스 거부 | | Dynamics 365 | 긴급 | 스푸핑 | | Azure DevOps | 중요 | 원격 코드 실행 | | Microsoft Azure | 중요 | 권한 상승 | | System Center | 중요 | 권한 상승 | [참고 사이트] [1] (한글) https://msrc.microsoft.com/update-guide/ko-kr/ [2] (영문) https://msrc.microsoft.com/update-guide/en-us/ [3] https://msrc.microsoft.com/update-guide/ko-kr/releaseNote/2024-Feb o 취약점 요약 정보 | 제품 카테고리 | CVE 번호 | CVE 제목 | | --- | --- | --- | | Microsoft WDAC OLE DB provider for SQL | CVE-2024-21420 | SQL Server용 Microsoft WDAC OLE DB 공급자 원격 코드 실행 취약성 | | Microsoft Office | CVE-2024-21413 | Microsoft Outlook 원격 코드 실행 취약성 | | Internet Shortcut Files | CVE-2024-21412 | 인터넷 바로가기 파일 보안 기능 바이패스 취약성 | | Microsoft Exchange Server | CVE-2024-21410 | Microsoft Exchange Server 권한 상승 취약성 | | Microsoft Windows | CVE-2024-21406 | Windows 인쇄 서비스 스푸핑 취약성 | | Windows Message Queuing | CVE-2024-21405 | Microsoft MSMQ(메시지 큐) 권한 상승 취약성 | | .NET | CVE-2024-21404 | .NET 서비스 거부 취약성 | | Microsoft Azure Kubernetes Service | CVE-2024-21403 | Microsoft Azure Kubernetes Service Confidential Container 권한 상승 취약성 | | Microsoft Office Outlook | CVE-2024-21402 | Microsoft Outlook 권한 상승 취약성 | | Azure Active Directory | CVE-2024-21401 | Microsoft Entra Jira S

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.
Patch available
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
A mitigation or workaround reference is available from the source linked below; validate it against the affected product and version.
04

Evidence and provenance

Published 13 Feb 2024 · Last source change 10 Aug 2026, 17:52 UTC · CWE-20 · Improper Input Validation

CVE recordCVE.org · 5.2
CVSS sourceCNA
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-2024-19122
Product sourceCISA KEV
Remediation sourceCVE/CNA references
CWE sourceOther authority
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. Affected versionsThe structured affected or fixed version information changed.
    Before
    16.0.1 < https://aka.ms/OfficeSecurityReleases; 16.0.0 < 16.0.5435.1001; 19.0.0 < https://aka.ms/OfficeSecurityReleases · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    Microsoft 365 Apps for Enterprise: 16.0.1 < https://aka.ms/OfficeSecurityReleases; Microsoft Office 2016: 16.0.0 < 16.0.5435.1001; Microsoft Office 2019: 19.0.0 < https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC 2021: 16.0.1 < https://aka.ms/OfficeSecurityReleases · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Added to CISA KEV
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2024-19122↗CISA KEV record↗CVE authority or vendor reference↗Mitigation reference↗Public exploit reference↗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-2024-21413 · cve.blacktree.nl