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

Researchers disclosed a flaw in Opera GX's automatic GX Mods installation that let a malicious site silently add a .crx mod whose CSS, applied across all visited pages, could use XS-Leak (cross-site leak) techniques to exfiltrate data such as a signed-in user's Gmail address. Opera patched the issue in Opera GX 130.0.5847.89, paid a P1 bounty, and stated it found no evidence of real-world exploitation.