security-review-owasp-xs-leaks

Cross-site information leaks in authenticated web flows are detected by validating framing controls, response normalization, browser-context isolation, and cross-origin request filtering. Reviewers examine fetch metadata, postMessage handlers, and cache-sensitive responses for observable state changes.

XS-Leaks are cross-site information leaks that reveal authentication state, membership, or protected workflow details through browser-observable behavior. They exploit timing, redirect, content-length, and cache differences in framed pages, navigation targets, and postMessage handlers.

Reviewing Fetch Metadata and SameSite cookie isolation involves examining request validation handlers for cross-origin filtering weaknesses. Evidence-based validation confirms whether sensitive pages can be embedded, enumerated, or distinguished across origins through framing or browsing-context issues.

PostMessage origin validation and framing controls need checking when assessing authenticated dashboards, webhook receivers, or admin pages. This review confirms whether these targets leak state through browser side channels like cache-sensitive responses and cross-origin interactions.

Analyzing response and cache differences that expose state changes requires examining timing, redirect, and content-length variations. This evidence-based approach identifies whether cache-sensitive responses leak authentication state or protected workflow details to cross-site attackers.

Yes, reviewing CORP and COOP headers prevents browser isolation bypasses by validating cross-origin request filtering and browsing-context isolation. This confirms whether sensitive pages can be embedded, enumerated, or distinguished across origins through framing or browsing-context issues.