What happened
Lightpanda ignored standard fetch/XHR credential-scoping directives, sending session cookies on every outbound request regardless of the requested credentials policy.
Why it matters
For an AI agent using Lightpanda to browse the web on a user's behalf, this bug leaks authenticated session cookies to any site the agent visits, turning routine agentic browsing into a credential-exfiltration vector.
Attack vector
Lightpanda's fetch() and XMLHttpRequest implementations unconditionally attached session cookies to every HTTP request, ignoring credentials: omit/same-origin/include and XMLHttpRequest.withCredentials directives, leaking session cookies to third-party origins.
Affected systems
Lightpanda prior to 0.2.9
Mitigation
Upgrade to Lightpanda 0.2.9 or later.