Proxy Auto-Config (PAC) files can specify a JavaScript function called for all URL requests with the full URL path which exposes more information than would be sent to the proxy itself in the case of HTTPS. Normally the Proxy Auto-Config file is specified by the user or machine owner and presumed to be non-malicious, but if a user has enabled Web Proxy Auto Detect (WPAD) this file can be served remotely. This vulnerability affects Firefox < 51.
Los archivos PAC (Proxy Auto-Config) pueden especificar una función JavaScript llamada para todas las peticiones URL con la ruta de URL completa, lo que expone más información que sería enviada al propio proxy en el caso de HTTPS. Normalmente, el archivo PAC es especificado por el usuario o propietario de la máquina y se cree que no es malicioso, pero si un usuario tiene WPAD (Web Proxy Auto Detect) habilitado, este archivo puede servirse de forma remota. La vulnerabilidad afecta a Firefox en versiones anteriores a la 51.
USN-3175-1 fixed vulnerabilities in Firefox. The update caused a regression on systems where the AppArmor profile for Firefox is set to enforce mode. This update fixes the problem. Multiple memory safety 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, or execute arbitrary code. JIT code allocation can allow a bypass of ASLR protections in some circumstances. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit this to cause a denial of service via application crash, or execute arbitrary code. Nicolas GrAgoire discovered a use-after-free when manipulating XSL in XSLT documents in some circumstances. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit this to cause a denial of service via application crash, or execute arbitrary code. Atte Kettunen discovered a memory corruption issue in Skia in some circumstances. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit this to cause a denial of service via application crash, or execute arbitrary code. Various other issues were also addressed.
