Planned Fix

CVE-2026-21520

Microsoft Copilot Studio Pre-Auth Info Disclosure

Summary

Microsoft Copilot Studio is a low-code platform for building AI agents and agent flows. This cloud-service flaw let unauthenticated network attackers view sensitive information from Copilot Studio without any user interaction. The impact is confidentiality loss rather than code execution or service disruption.

Why Planned Fix?

4/6

No authentication required

Commonly internet-facing deployment

No user interaction needed

Exploitable in default configuration

No active exploitation or PoC

Not a high impact vulnerability

Exploitation Details

Type

Unknown

Is exploitable with default configuration?

Yes

Is authentication needed?

PoC / Exploit

Impact

Read sensitive information from Copilot Studio

Data Disclosure

Exploitation Requirements

None — vulnerable in default configuration

Exploitation Process

An attacker sends crafted, unauthenticated requests to Copilot Studio service endpoints. If the vulnerable request path is reached, the service returns information that should have been access-controlled. Success is verified by receiving sensitive data without first authenticating or having an authorized session.

Detection Resources

Manual Detection

Script Detection

Scanner Detection

Tenable Nessus

Affected Software

Vendor:Microsoft

Product	Affected Versions
Microsoft Copilot Studio	all versions

Description

Microsoft Copilot Studio is a graphical, low-code tool for building AI agents and agent flows that can connect to other data sources and business systems.

Deployment:Commonly internet-facing

Protocol:HTTPS

Ports:443

Affected ComponentCopilot Studio cloud service backend and web authoring portal handling agent and information-access requests.

Copilot Studio cloud service backend and web authoring portal handling agent and information-access requests.

Affected Endpoints(1)https://copilotstudio.microsoft.com

1.https://copilotstudio.microsoft.com

Enterprise Usage

Very Low

Low

Medium

High

Very High

Vendor Size:Big

Vendor Notifications

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21520 https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-21520.json

Remediation

Workaround

Not available

Patch

Not available

Update

Not available

Threat Intelligence

EPSS Score0.1%

Probability of exploitation in the next 30 days

EPSS Percentile26%

Worse than 26% of all CVEs

Last updated: Loading...

CISA KEV

Not Listed

Active Exploitation

No Evidence

Threat Actors

No known threat actors

Detection Rules

No detection rules available

NVD Data

Published: Loading...Modified: Loading...

Description Summary

Exposure of Sensitive Information to an Unauthorized Actor in Copilot Studio allows a unauthenticated attacker to view sensitive information through network attack vector

CVSS Base Score

7.5

High

CVSS Vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)

Attack Vector (AV)

Physical

Local

Adjacent

Network

Attack Complexity (AC)

High

Low

Privileges Required (PR)

High

Low

None

User Interaction (UI)

Required

None

Scope (S)

Unchanged

Changed

Confidentiality (C)

None

Low

High

Integrity (I)

None

Low

High

Availability (A)

None

Low

High

CWE:CWE-77 Command Injection

NVD:CVE-2026-21520

Version From:—

Version Upto:—

Affected Software (CPE) (1)

•cpe:2.3:a:microsoft:copilot_studio:-:*:*:*:*:*:*:*

Sources

Source	Article
msrc.microsoft.com	Copilot Studio Information Disclosure Vulnerability - CSAF
msrc.microsoft.com	Security Update Guide - CVE-2026-21520
nvd.nist.gov	CVE-2026-21520 Detail
learn.microsoft.com	Overview - Microsoft Copilot Studio
learn.microsoft.com	Configure user authentication in Copilot Studio
tenable.com	CVE-2026-21520

Priority History

Planned FixLoading...

Initial analysis