Mailvelope prior to 3.3.0 allows private key operations without user interaction via its client-API. By modifying an URL parameter in Mailvelope, an attacker is able to sign (and encrypt) arbitrary messages with Mailvelope, assuming the private key password is cached. A second vulnerability allows an attacker to decrypt an arbitrary message when the GnuPG backend is used in Mailvelope.

Mailvelope prior to 3.3.0 allows private key operations without user interaction via its client-API. By modifying an URL parameter in Mailvelope, an attacker is able to sign (and encrypt) arbitrary messages with Mailvelope, assuming the private key password is cached. A second vulnerability allows an attacker to decrypt an arbitrary message when the GnuPG backend is used in Mailvelope.