Threat
BragJack: One Extension Hijacks Five Browsers’ AI Agents – Lab Space
First reported · Discovered cloudsecurityalliance.org
Page published
Earliest dated coverage: 22 Sep 2026 · First observed: 20 Oct 2026 · Latest dated coverage: 22 Sep 2026
Coverage timeline
Single-source research — one report is available.
Why it matters
BragJack shows how browser extensions can cross into privileged AI-agent control channels without defeating model guardrails, making browser updates and extension-permission review important defensive measures.
BragJack is a demonstrated attack that lets a malicious browser extension hijack AI agents in Chrome, Perplexity Comet, Microsoft Edge, Opera Neon, and Claude in Chrome. Its “Prompt Forcing” technique abuses already-granted extension permissions to reach trusted agent-control channels, potentially enabling file access, data exfiltration, camera or microphone activation, and authenticated actions. The report says all five vendors remediated the demonstrated behaviors, including Chrome’s CVE-2026-0628 and Edge’s CVE-2026-55945.