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Open Redirect Elevation of Privilege in Microsoft 365 Copilot Business Chat
CVE-2026-47645 is an elevation of privilege vulnerability in Microsoft 365 Copilot's Business Chat caused by an open redirect condition. The flaw allows Business Chat to redirect a user or workflow to an untrusted site, creating a trust-boundary failure that can be leveraged by an unauthorized attacker. Microsoft classifies the issue as affecting Microsoft 365 Copilot and specifically identifies Business Chat as the vulnerable component. Available scoring metadata indicates low attack complexity, low privileges required, no user interaction, and high impact to confidentiality, integrity, and availability.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation can allow an unauthorized attacker to achieve elevation of privilege in the context of Microsoft 365 Copilot Business Chat. The published scoring metadata indicates potential high impact across confidentiality, integrity, and availability, implying that exploitation could enable access or actions beyond the attacker's intended authorization boundary within the affected service context.
If you can’t patch tonight, do this now.
No customer action is required according to the vendor. As a general defensive measure, organizations should continue to enforce least privilege, monitor Microsoft 365 Copilot usage for anomalous privilege changes or suspicious redirection-related activity, and follow any additional Microsoft service-side guidance if updated.
Patch, then assume compromise.
Microsoft has stated that the issue has already been fully mitigated in the cloud service. No customer-applied patch or configuration change is required. Organizations should verify they are using the supported Microsoft 365 Copilot service and monitor Microsoft security communications for any follow-on guidance.
No public exploits tracked yet. Mallory keeps watching.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
8 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.