CVE-2025-1936: 
Mozilla Firefox vulnerability analysis and mitigation

CVE-2025-1936 is a security vulnerability discovered in Mozilla Firefox and Thunderbird browsers that affects Firefox < 136, Firefox ESR < 128.8, Thunderbird < 136, and Thunderbird < 128.8. The vulnerability was disclosed on March 4, 2025, and was reported by security researcher Surya Dev Singh (Mozilla Advisory).

The vulnerability involves the handling of jar: URLs that retrieve local file content packaged in ZIP archives. The issue occurs when a null character (%00) and a fake extension are added to a jar: URL - the null character and everything after it was ignored when retrieving content from the archive, but the fake extension after the null was used to determine the content type. Mozilla has classified this vulnerability as having a low severity impact (Mozilla Advisory).

This vulnerability could be exploited to hide malicious code in a web extension by disguising it as a different type of content, such as an image. The impact is particularly relevant in browser or browser-like contexts where jar: URLs are processed (Mozilla Advisory).

The vulnerability has been patched in Firefox 136, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8. Users are advised to update their browsers to these versions or later to mitigate the vulnerability (Red Hat Advisory).