An issue was discovered in the org.telegram.messenger application 4.8.11 for Android. The FingerprintManager class for Biometric validation allows authentication bypass through the callback method from onAuthenticationFailed to onAuthenticationSucceeded with null, because the fingerprint API in conjunction with the Android keyGenerator class is not implemented. In other words, an attacker could authenticate with an arbitrary fingerprint.  NOTE: the vendor indicates that this is not an attack of interest within the context of their threat model, which excludes Android devices on which rooting has occurred