CVE-2025-11716 is a security vulnerability identified in Mozilla Firefox on Android platforms, affecting versions prior to 144, as well as Thunderbird prior to 144. The vulnerability arises from improper enforcement of sandbox restrictions on iframes. Specifically, sandboxed iframes, which are intended to isolate embedded content and restrict its capabilities, were able to open links in external applications without requiring the explicit 'allow-' permission that normally governs such behavior. This bypass allows malicious web content embedded within these iframes to launch external apps on the Android device without user consent or proper security checks. The impact of this flaw is significant because it undermines the security model of sandboxed iframes, potentially enabling attackers to trigger actions in other apps, which could lead to unauthorized data access, privilege escalation, or further exploitation of the device. The vulnerability does not require user authentication and can be triggered simply by visiting a malicious webpage containing the crafted iframe. Although no known exploits have been reported in the wild as of the publication date, the vulnerability's nature makes it a serious concern, especially for users on mobile devices where app interactions are common. The flaw affects Firefox and Thunderbird on Android, both widely used applications, increasing the potential attack surface. Mozilla has acknowledged the issue and plans to address it in version 144 and later. Until patches are applied, users remain vulnerable to potential exploitation. The absence of a CVSS score necessitates an independent severity assessment based on the vulnerability's characteristics.

For European organizations, this vulnerability poses a risk primarily to users operating Firefox or Thunderbird on Android devices. The ability for sandboxed iframes to open external apps without permission could be exploited to launch malicious apps or trigger unintended actions, potentially leading to data leakage, unauthorized access to sensitive information, or further compromise of mobile endpoints. Organizations with mobile workforces relying on Firefox for secure browsing or Thunderbird for email on Android devices are particularly at risk. This could impact confidentiality if sensitive data is exposed through external apps, and integrity if unauthorized actions are performed. Availability impact is limited but could occur if malicious apps are launched that disrupt device operation. Given the widespread use of Firefox in Europe and the increasing reliance on mobile devices for business operations, the vulnerability could facilitate targeted attacks against corporate users, especially in sectors handling sensitive data such as finance, healthcare, and government. The lack of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits once the vulnerability is public. Failure to patch promptly could lead to increased exposure to phishing or drive-by download attacks leveraging this flaw.

European organizations should take proactive steps to mitigate this vulnerability. First and foremost, ensure that all Firefox and Thunderbird installations on Android devices are updated to version 144 or later as soon as patches become available from Mozilla. Until patches are deployed, consider restricting access to untrusted websites, especially those that may host malicious iframes, through network-level filtering or endpoint security solutions. Implement mobile device management (MDM) policies to enforce application updates and control app permissions rigorously. Educate users about the risks of visiting untrusted websites and the importance of applying updates promptly. Additionally, review and tighten Content Security Policy (CSP) settings where possible to limit iframe sources and permissions. Monitor network traffic for unusual app launch behaviors that could indicate exploitation attempts. Finally, coordinate with IT and security teams to integrate vulnerability scanning and patch management processes specifically targeting mobile browsers and email clients.