CVE-2019-11755

Un mensaje S/MIME diseñado que consta de una capa de cifrado interna y una capa SignedData externa se mostró con firma digital válida, aunque el firmante podría no haber tenido acceso al contenido del mensaje cifrado y podría haber eliminado una firma diferente del mensaje cifrado. Las versiones anteriores solo habían suprimido el despliegue de una firma digital para mensajes con una capa externa multiparte y firmada. Esta vulnerabilidad afecta a Thunderbird versiones anteriores a 68.1.1.

USN-4202-1 fixed vulnerabilities in Thunderbird. After upgrading, Thunderbird created a new profile for some users. This update fixes the problem. It was discovered that a specially crafted S/MIME message with an inner encryption layer could be displayed as having a valid signature in some circumstances, even if the signer had no access to the encrypted message. An attacker could potentially exploit this to spoof the message author. Multiple security issues were discovered in Thunderbird. If a user were tricked in to opening a specially crafted website in a browsing context, an attacker could potentially exploit these to cause a denial of service, bypass security restrictions, bypass same-origin restrictions, conduct cross-site scripting attacks, or execute arbitrary code. A heap overflow was discovered in the expat library in Thunderbird. If a user were tricked in to opening a specially crafted message, an attacker could potentially exploit this to cause a denial of service, or execute arbitrary code.