Microsoft 365 Word Copilot control sequence

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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5.8$5k-$25k0.00

Summaryinfo

A vulnerability labeled as problematic has been found in Microsoft 365 Word Copilot. This affects an unknown part. Executing a manipulation can lead to control sequence. This vulnerability is registered as CVE-2026-21521. It is possible to launch the attack remotely. No exploit is available. This product is provided as a managed service, meaning users do not have the ability to maintain vulnerability countermeasures themselves.

Detailsinfo

A vulnerability was found in Microsoft 365 Word Copilot (the affected version unknown). It has been declared as problematic. This vulnerability affects an unknown part. The manipulation with an unknown input leads to a control sequence vulnerability. The CWE definition for the vulnerability is CWE-150. The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as escape, meta, or control character sequences when they are sent to a downstream component. As an impact it is known to affect confidentiality. CVE summarizes:

Improper neutralization of escape, meta, or control sequences in Copilot allows an unauthorized attacker to disclose information over a network.

The advisory is shared for download at msrc.microsoft.com. This vulnerability was named CVE-2026-21521 since 12/30/2025. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 01/25/2026).

This product is available as a managed service. Users are not able to maintain vulnerability countermeasures themselves.

The vulnerability is also documented in the databases at CNNVD (CNNVD-202601-3928), EUVD (EUVD-2026-4498) and CERT Bund (WID-SEC-2026-0201). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Microsoft Azure
  • Microsoft 365 Copilot
  • Microsoft Entra

Productinfo

Vendor

Name

License

Managed Service

  • yes

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.8
VulDB Meta Temp Score: 5.8

VulDB Base Score: 4.3
VulDB Temp Score: 4.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.4
CNA Vector (microsoft): 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Control sequence
CWE: CWE-150 / CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Status: 🔍

0-Day Time: 🔒

Timelineinfo

12/30/2025 CVE reserved
01/23/2026 +24 days Advisory disclosed
01/23/2026 +0 days VulDB entry created
01/25/2026 +2 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-21521 (🔒)
GCVE (CVE): GCVE-0-2026-21521
GCVE (VulDB): GCVE-100-342520
EUVD: 🔒
CERT Bund: WID-SEC-2026-0201 - Microsoft Azure, Copilot und Entra: Mehrere Schwachstellen
CNNVD: CNNVD-202601-3928 - Microsoft 365 Word Copilot 安全漏洞

Entryinfo

Created: 01/23/2026 08:11
Updated: 01/25/2026 15:30
Changes: 01/23/2026 08:11 (60), 01/23/2026 15:25 (6), 01/24/2026 04:39 (7), 01/24/2026 12:59 (1), 01/25/2026 14:14 (1), 01/25/2026 15:30 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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