CVE-2019-9791

El sistema de inferencia de tipos permite la recopilación de funciones que pueden generar confusiones de tipo entre objetos arbitrarios cuando se compilan por medio del compilador IonMonkey just-in-time (JIT) y cuando se ingresa a la función constructor mediante el reemplazo en la pila (OSR). Esto permite una posible lectura y escritura arbitrarias de objetos durante un bloqueo explotable. Esta vulnerabilidad afecta a Thunderbird versiones <60.6, Firefox ESR versiones <60.6 y Firefox versiones <66.

USN-3918-1 fixed vulnerabilities in Firefox. The update caused web compatibility and performance issues with some websites. This update fixes the problem. Multiple security issues were discovered in Firefox. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit these to cause a denial of service via application crash, denial of service via successive FTP authorization prompts or modal alerts, trick the user with confusing permission request prompts, obtain sensitive information, conduct social engineering attacks, or execute arbitrary code. A mechanism was discovered that removes some bounds checking for string, array, or typed array accesses if Spectre mitigations have been disabled. If a user were tricked in to opening a specially crafted website with Spectre mitigations disabled, an attacker could potentially exploit this to cause a denial of service, or execute arbitrary code. It was discovered that Upgrade-Insecure-Requests was incorrectly enforced for same-origin navigation. An attacker could potentially exploit this to conduct man-in-the-middle attacks. Various other issues were also addressed.