CVE-2024-3863 in Firefox
Summary
by MITRE • 04/16/2024
The executable file warning was not presented when downloading .xrm-ms files. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.* This vulnerability affects Firefox < 125 and Firefox ESR < 115.10.
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Analysis
by VulDB Data Team • 11/23/2025
The vulnerability described in CVE-2024-3863 represents a critical security flaw in Firefox's handling of specific file types on Windows operating systems. This issue stems from the browser's failure to properly display executable file warnings during the download of .xrm-ms files, which are Windows Resource Manager files that can contain executable content. The absence of these warnings creates a significant risk for users who may unknowingly download and execute potentially malicious code without proper security awareness.
The technical root cause of this vulnerability lies in Firefox's implementation of file type handling and user interface prompts. When users attempt to download .xrm-ms files, the browser should present a clear warning about the executable nature of these files, similar to how it handles other potentially dangerous file types. However, due to a flaw in the browser's security prompt logic, this warning mechanism fails to activate specifically for .xrm-ms files on Windows systems, creating a gap in the user's security awareness process. This behavior aligns with CWE-116, which addresses improper handling of potentially dangerous data, and represents a failure in secure input validation and user interface security prompts.
The operational impact of this vulnerability extends beyond simple user inconvenience to represent a serious threat vector for social engineering attacks and malware distribution. Attackers could exploit this weakness by disguising malicious payloads within .xrm-ms files, knowing that users would not receive the expected security warnings. This vulnerability particularly affects organizations and individuals who rely on Firefox for web browsing, as it undermines the browser's security model and creates potential entry points for various attack vectors including phishing campaigns, drive-by downloads, and targeted malware delivery. The risk is compounded by the fact that .xrm-ms files are often associated with legitimate Windows components, making them more likely to be trusted by users who may not recognize the security implications.
This vulnerability directly impacts Firefox versions prior to 125 and Firefox ESR versions prior to 115.10, creating a window of exposure for users who have not yet updated their browsers. The fix implemented by Mozilla addresses the missing warning prompt mechanism and ensures that users receive appropriate security notifications when downloading .xrm-ms files. Organizations should prioritize immediate deployment of these updates to mitigate the risk of exploitation, as the vulnerability falls within the ATT&CK framework's T1204.002 technique for legitimate program execution, where adversaries leverage trusted system components to execute malicious code. The remediation strategy should include comprehensive browser update policies, security awareness training for users, and monitoring for suspicious download activities that may indicate exploitation attempts.