By checking the result of calls to window.open with specifically set protocol handlers, an attacker could determine if the application which implements that protocol handler is installed. This vulnerability affects Firefox < 131, Firefox ESR < 128.3, Thunderbird < 128.3, and Thunderbird < 131.

References

• https://nvd.nist.gov/vuln/detail/CVE-2024-9398
• https://bugzilla.mozilla.org/show_bug.cgi?id=1881037
• https://www.mozilla.org/security/advisories/mfsa2024-46
• https://www.mozilla.org/security/advisories/mfsa2024-47
• https://www.mozilla.org/security/advisories/mfsa2024-49
• https://www.mozilla.org/security/advisories/mfsa2024-50