Where. transport/rest/src/main/java/org/a2aproject/sdk/transport/rest/handler/RestHandler.java:676 in parseRequestBody
What. The parseRequestBody method logs the entire JSON request body at SEVERE level when JsonFormat.parser().merge() throws InvalidProtocolBufferException. This method is called from createTaskPushNotificationConfiguration (line 377), where the body contains client-supplied push notification bearer tokens (field token) and authentication credentials (field authentication.credentials). These secrets are written to server log files in full.
Exploit scenario. A client creates a push notification configuration by POSTing to /v1/tenants/{tenant}/tasks/{taskId}/pushNotificationConfigs with a body containing {"url": "https://client.example.com/webhook", "token": "secret-bearer-token", "authentication": {"scheme": "Bearer", "credentials": "oauth-access-token"}, "extraField": "value"}. The extra field causes JsonFormat.parser().merge() to throw InvalidProtocolBufferException. The entire body including secret-bearer-token and oauth-access-token is logged at SEVERE level. An attacker with log access retrieves the cleartext credentials.
Preconditions.
- Attacker must have access to server log files (centralized logging, log aggregation, shared infrastructure, or insider access)
- Push notification capability must be enabled
- A request body must fail protobuf deserialization while being valid JSON (unknown fields with strict parsing, schema mismatches)
Fix. Do not log the raw request body. Log only a sanitized summary — body length and content type, not content. Replace the log call with something like: log.log(Level.SEVERE, "Error parsing JSON request body (length={0})", body != null ? body.length() : 0).
Verification. 3/3 lens verifiers confirmed.