Opera GX Flaw Let Malicious Sites Auto-Install Mods to Steal Data From Visited Pages

Researchers found a flaw in Opera GX, the gaming-focused version of the Opera browser, that let a malicious website silently install a browser add-on and use it to lift specific data from the pages a victim visits. In a proof of concept, they reconstructed a signed-in user's full Gmail address from a single visit, with no click. Opera has patched the flaw and says it found no evidence that

The reported Opera GX flaw allowed a malicious website to silently install a browser add-on and exfiltrate sensitive data from pages a user visited, including reconstructing a logged-in user's full Gmail address from a single page visit without any click interaction, before being patched by Opera. This is a classic client-side data leakage issue at the browser/extension boundary, not an AI-specific vulnerability, but it directly affects the confidentiality of data AI agents might rely on if run in-browser or alongside such extensions. From a CyberSE.AI perspective, teams building or deploying AI agents in browser contexts should treat the browser and its extension ecosystem as part of their attack surface, harden permissions and extension interactions, and use continuous red teaming to test for silent data exfiltration paths that could leak user or contextual data used by AI-powered workflows.