Teams
CVE-2026-21535
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessSend unauthenticated network request to Teams endpoint
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ExploitBypass access control checks
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ExecutionRetrieve sensitive user information and metadata
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ImpactModify limited data fields
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Access control enforcement
MITRE ATT&CK
1 technique across 1 tactic: Defense Evasion The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | No special conditions — remote unauthenticated exploitation against default Microsoft Teams deployments with accessible network endpoints and improper access control enforcement. |
| Impact | CVSS 8.2 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Exploitation no authentication required. Exploitable via remote/network. |
| Exploit ScenarioDerived | A remote attacker without authentication could exploit this vulnerability to compromise the affected system. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Microsoft Teams contains an access control vulnerability that enables unauthenticated remote attackers to extract sensitive information without user interaction. The flaw affects Teams deployments and carries a high severity rating, though no patch is currently available. Exploitation requires only network access with no additional prerequisites, making this a significant risk for organizations using the platform.
Earlier versions of this analysis (1)
Improper access control in Microsoft Teams allows an unauthorized attacker to disclose information over a network. [CVSS 8.2 HIGH]
RemediationAI
Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in microsoft
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-284 (Improper Access Control). Affects Teams. Improper access control in Microsoft Teams allows an unauthorized attacker to disclose information over a network.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionCVE.org
Improper access control in Microsoft Teams allows an unauthorized attacker to disclose information over a network.
Executive ViewAI
CVE-2026-21535 is a high-severity access control flaw in Microsoft Teams that could allow attackers to access sensitive organizational information without authorization. With no patch currently available, immediate mitigation steps are required to protect confidential communications and data shared within Teams.
Disable external sharing in Teams; restrict guest access; implement conditional access policies limiting Teams access to managed devices only; enforce network segmentation isolating Teams traffic; enable enhanced audit logging and DLP policies to monitor data exfiltration; consider temporary migration of highly sensitive communications to alternative secure channels; implement IP whitelisting at the network perimeter; monitor Teams activity for unauthorized access patterns.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Affected Products (CPE)CVE.org
Privilege elevation in Microsoft Teams lets a remote, unauthenticated attacker gain unauthorized access across a network
Path-traversal-driven remote code execution affects the Microsoft Teams client for Android in all builds prior to 1.0.0.
A library injection vulnerability exists in Microsoft Teams (work or school) 24046.2813.2770.1094 for macOS. Rated criti
A library injection vulnerability exists in the WebView.app helper app of Microsoft Teams (work or school) 24046.2813.27
A library injection vulnerability exists in the com.microsoft.teams2.modulehost.app helper app of Microsoft Teams (work
Privilege elevation in Microsoft Teams allows an authenticated attacker with low-level access to bypass authentication c
Heap buffer overflow in libwebp in Google Chrome prior to 116.0.5845.187 and libwebp 1.3.2 allowed a remote attacker to
Cross-site scripting in Microsoft Teams for Android (versions below 1.0.76.202611302) enables an authenticated attacker
Cryptographic signature spoofing in Microsoft Teams exposes enterprise collaboration environments to unauthenticated ide
The Microsoft Teams online service contains a stored cross-site scripting vulnerability in the displayName parameter tha
Microsoft Teams Remote Code Execution Vulnerability. Rated high severity (CVSS 8.8), this vulnerability is remotely expl
Microsoft Teams Remote Code Execution Vulnerability. Rated high severity (CVSS 8.8), this vulnerability is remotely expl
GitHub PoC
Exploit-DB