CVE-2025-6429

Description

Firefox could have incorrectly parsed a URL and rewritten it to the youtube.com domain when parsing the URL specified in an `embed` tag. This could have bypassed website security checks that restricted which domains users were allowed to embed. This vulnerability affects Firefox < 140, Firefox ESR < 128.12, Thunderbird < 140, and Thunderbird < 128.12.

References

https://www.mozilla.org/security/advisories/mfsa2025-55/

https://www.mozilla.org/security/advisories/mfsa2025-54/

https://www.mozilla.org/security/advisories/mfsa2025-53/

https://www.mozilla.org/security/advisories/mfsa2025-51/

https://bugzilla.mozilla.org/show_bug.cgi?id=1970658

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

EPSS