An open redirect vulnerability in M365 Copilot allows an unauthorized attacker to manipulate network traffic, potentially leading to unauthorized privilege escalation.

The application fails to validate destination URLs during redirection, allowing an open redirect flaw. An attacker can exploit this to redirect users to malicious sites, which may subsequently be used in more complex attack chains to achieve privilege escalation.

The CVSS score of 9.3 highlights the critical nature of this flaw. By leveraging the trust in the M365 environment, attackers can perform effective phishing or man-in-the-middle attacks to elevate privileges, potentially gaining unauthorized access to sensitive corporate data and administrative functions.

Immediate Action: Apply all security patches and configuration updates released by Microsoft for the M365 Copilot suite.

Proactive Monitoring: Monitor network and proxy logs for suspicious redirection patterns or traffic directed toward unrecognized, external domains.

Compensating Controls: Use URL filtering and browser-based security policies to restrict or warn users about redirects to non-sanctioned domains.

Public Exploit Available: Unknown

Organizations should monitor official Microsoft security bulletins for patches related to M365 Copilot. Given the high severity of potential privilege escalation, immediate application of vendor-provided security updates is strongly advised to protect sensitive internal environments.