Microsoft Teams access control

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.6$0-$5k0.00

Summaryinfo

A vulnerability was found in Microsoft Teams. It has been rated as critical. Affected by this vulnerability is an unknown functionality. The manipulation leads to access control. This vulnerability is traded as CVE-2026-21535. It is possible to initiate the attack remotely. There is no exploit available. This product is a managed service, so users are unable to manage vulnerability countermeasures on their own.

Detailsinfo

A vulnerability was found in Microsoft Teams (version unknown). It has been rated as critical. This issue affects an unknown function. The manipulation with an unknown input leads to a access control vulnerability. Using CWE to declare the problem leads to CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Improper access control in Microsoft Teams allows an unauthorized attacker to disclose information over a network.

It is possible to read the advisory at msrc.microsoft.com. The identification of this vulnerability is CVE-2026-21535 since 12/30/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/22/2026). The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

Vendor

Name

License

Managed Service

  • yes

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.7
VulDB Meta Temp Score: 7.6

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔒

CNA Base Score: 8.2
CNA Vector (microsoft): 🔒

CVSSv2info

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

Exploitinginfo

Class: Access control
CWE: CWE-284 / CWE-266
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
02/20/2026 +52 days Advisory disclosed
02/20/2026 +0 days VulDB entry created
02/22/2026 +2 days VulDB entry last update

Sourcesinfo

Vendor: microsoft.com

Advisory: msrc.microsoft.com
Status: Confirmed

CVE: CVE-2026-21535 (🔒)
GCVE (CVE): GCVE-0-2026-21535
GCVE (VulDB): GCVE-100-347039

Entryinfo

Created: 02/20/2026 01:27
Updated: 02/22/2026 04:54
Changes: 02/20/2026 01:27 (62), 02/22/2026 04:54 (9)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

Discussion

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