How ‘Reprompt’ Attack Let Hackers Steal Data From Microsoft Copilot

Varonis found a “Reprompt” attack that let a single link hijack Microsoft Copilot Personal sessions and exfiltrate data; Microsoft patched it in January 2026.

A single click mounted a covert, multistage attack against Copilot

Microsoft has fixed a vulnerability in its Copilot AI assistant that allowed hackers to pluck a host of sensitive user data ...

How a simple link allowed hackers to bypass Copilot's security guardrails - and what Microsoft did about it

Reprompt impacted Microsoft Copilot Personal and, according to the team, gave "threat actors an invisible entry point to perform a data‑exfiltration chain that bypasses enterprise security controls ...

Malicious GhostPoster browser extensions found with 840,000 installs

Another set of 17 malicious extensions linked to the GhostPoster campaign has been discovered in Chrome, Firefox, and Edge ...

Reprompt attack hijacked Microsoft Copilot sessions for data theft

Researchers identified an attack method dubbed "Reprompt" that could allow attackers to infiltrate a user's Microsoft Copilot session and issue commands to exfiltrate sensitive data.