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

CVE-2026-21535

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

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

HIGH · CVSS 8.2 EPSS 0.0009
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules5 YARA rules0
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Weakness Classification

CWE-284Improper Access Control
▤

Affected Products & Versions

1
microsoft teamsall versions
◈

Sigma Hunt Rules

5
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighMalicious DLL File Dropped in the Teams or OneDrive Folder
producthighSuspicious Teams Application Related ObjectAcess Event
productmediumMicrosoft Teams Sensitive File Access By Uncommon Applications
productmediumRenamed Microsoft Teams Execution
productmediumPotentially Suspicious Command Targeting Teams Sensitive Files
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Scoring & Timeline

8.2
HIGH · CVSS v3.1 · secure@microsoft.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD19 Feb 2026 · 11:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
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Vendor Advisories

1
msrcCVE-2026-21535Information Disclosure
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