CVE-2021-38503

Las reglas del sandbox de iframe no se aplicaban correctamente a las hojas de estilo XSLT, permitiendo a un iframe omitir restricciones como la ejecución de scripts o la navegación por el marco de nivel superior. Esta vulnerabilidad afecta a Firefox versiones anteriores a 94, Thunderbird versiones anteriores a 91.3 y Firefox ESR versiones anteriores a 91.3

The Mozilla Foundation Security Advisory describes this flaw as: The iframe sandbox rules were not correctly applied to XSLT stylesheets, allowing an iframe to bypass restrictions such as executing scripts or navigating the top-level frame.

Multiple security issues were discovered in Firefox. If a user were tricked into opening a specially crafted website, an attacker could potentially exploit these to cause a denial of service, bypass security restrictions, spoof the browser UI, confuse the user, conduct phishing attacks, or execute arbitrary code. It was discovered that the 'Copy Image Link' context menu action would copy the final image URL after redirects. If a user were tricked into copying and pasting a link for an embedded image that triggered authentication flows back to the page, an attacker could potentially exploit this to steal authentication tokens. Various other issues were also addressed.