Cross-origin messaging trust failure
A message handler trusts an unauthorized sender or leaks protected data to an unintended origin.
Candidate CWE: CWE-346
Test hypothesis#
Observe a legitimate postMessage exchange in a local controlled application. From a researcher frame/window, send its expected shape and change only sender origin; use a harmless state marker.
Evidence required#
The unauthorized sender triggers a protected action or receives the controlled private marker. Include window/frame relationship, message schema, origin checks, and normal-delivery prerequisites.
Rule out false positives#
A wildcard target on non-sensitive messages, a handler with no reachable security-sensitive action, or console-only invocation is not a complete finding.
Playbook and command references#
- Browser execution, cross-origin reads, and forged actions — Use real browser behavior to distinguish XSS, CSRF, CORS, and messaging failures from header-only leads.
Find the associated command snippets
Referenced by these target playbooks#
Report checklist#
- Capture the affected version, configuration, identities, and object ownership.
- Preserve a valid baseline and a negative control.
- Reproduce the forbidden data access, action, or state change on controlled fixtures.
- Explain the intended security rule and why the observed behavior violates it.
- State prerequisites, uncertainty, cleanup, and the smallest demonstrated impact.
Conditional ATT&CK mapping#
No direct ATT&CK mapping selected. Record the weakness and demonstrated impact without forcing an adversary-behavior classification. See the mapping guide.