Url redirection to untrusted site ('open redirect') in Microsoft 365 Copilot's Business Chat allows an unauthorized attacker to elevate privileges ove...
Description
Url redirection to untrusted site ('open redirect') in Microsoft 365 Copilot's Business Chat allows an unauthorized attacker to elevate privileges over a network
AI Analyst Comment
Remediation
Apply vendor security updates immediately. Monitor for exploitation attempts and review access logs.
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VENDOR: Microsoft
PRODUCT: 365 Copilot Business Chat
AFFECTED_VERSIONS: See vendor advisory for affected versions
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Description Summary:
Microsoft 365 Copilot's Business Chat is vulnerable to an open redirect, which can be leveraged by an unauthorized attacker to facilitate privilege escalation over a network.
Executive Summary:
An open redirect vulnerability in Microsoft 365 Copilot's Business Chat may allow unauthorized attackers to escalate privileges over a network.
Vulnerability Details
CVE-ID: CVE-2026-47645
Affected Software: Microsoft 365 Copilot
Affected Versions: See vendor advisory for affected versions
Vulnerability: The application contains an "open redirect" vulnerability where user-supplied input is not properly validated before redirecting the user to an untrusted site. This vulnerability can be chained with other techniques to achieve privilege escalation.
Business Impact
While an open redirect is often considered a lower-severity issue, the potential for privilege escalation elevates the risk profile, resulting in a CVSS score of 8.8. A successful exploit could lead to unauthorized access to sensitive corporate data within the M365 ecosystem, reputational damage, and the compromise of user accounts. The capability to escalate privileges makes this a significant threat to internal security controls.
Remediation Plan
Immediate Action: Apply all relevant Microsoft security updates immediately upon release to address the redirect flaw.
Proactive Monitoring: Monitor network and application logs for unexpected redirection patterns or users being routed to unrecognized external domains from the Business Chat interface.
Compensating Controls: Implement strict Content Security Policy (CSP) headers and maintain awareness training regarding suspicious links, even those originating from trusted internal interfaces.
Exploitation Status
Public Exploit Available: False
Analyst Notes: As of June 20, 2026, there is no public information indicating active exploitation of this vulnerability. However, due to the nature of the flaw, the potential for exploitation is high.
Analyst Recommendation
Microsoft 365 users should maintain a vigilant posture regarding security updates. Given the potential for privilege escalation, it is vital to apply patches as soon as they are made available by Microsoft. Organizations should also review their identity and access management policies to minimize the impact of potential privilege abuse.