Firebase JavaScript SDK utilizes a "FIREBASE_DEFAULTS" cookie to store configuration data, including an "_authTokenSyncURL" field used for session synchronization. If this cookie field is preset via an attacker by any other method, the attacker can manipulate the "_authTokenSyncURL" to point to their own server and it would allow an actor to capture user session data transmitted by the SDK. We recommend upgrading Firebase JS SDK at least to 10.9.0.

This vulnerability was a potential CSRF attack. When running the Firebase emulator suite, there is an export endpoint that is used normally to export data from running emulators. If a user was running the emulator and navigated to a malicious website with the exploit on a browser that allowed calls to localhost (ie Chrome before v94), the website could exfiltrate emulator data. We recommend upgrading past version 13.6.0 or commit  068a2b08dc308c7ab4b569617f5fc8821237e3a0 https://github.com/firebase/firebase-tools/commit/068a2b08dc308c7ab4b569617f5fc8821237e3a0

Jerome Gamez Firebase Admin SDK for PHP version from 3.2.0 to 3.8.0 contains a Incorrect Access Control vulnerability in src/Firebase/Auth/IdTokenVerifier.php does not verify for token signature that can result in JWT with any email address and user ID could be forged from an actual token, or from thin air. This attack appear to be exploitable via Attacker would only need to know email address of the victim on most cases.. This vulnerability appears to have been fixed in 3.8.1.