Firefox normally asks for confirmation before asking the operating system to find an application to handle a scheme that the browser does not support. It did not ask before doing so for the Usenet-related schemes news: and snews:. Since most operating systems don't have a trusted newsreader installed by default, an unscrupulous program that the user downloaded could register itself as a handler. The website that served the application download could then launch that application at will This vulnerability affects Firefox < 130, Firefox ESR < 128.2, and Firefox ESR < 115.15.

References

• https://nvd.nist.gov/vuln/detail/CVE-2024-8383
• https://bugzilla.mozilla.org/show_bug.cgi?id=1908496
• https://www.mozilla.org/security/advisories/mfsa2024-39
• https://www.mozilla.org/security/advisories/mfsa2024-40
• https://www.mozilla.org/security/advisories/mfsa2024-41
• https://www.mozilla.org/security/advisories/mfsa2024-43
• https://www.mozilla.org/security/advisories/mfsa2024-44