| Name | 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 and Firefox ESR < 128.12. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DSA-5950-1 |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|
| firefox (PTS) | sid | 140.0-1 | fixed |
| firefox-esr (PTS) | bullseye | 115.14.0esr-1~deb11u1 | vulnerable |
| bullseye (security) | 128.12.0esr-1~deb11u1 | vulnerable |
| bookworm | 128.10.0esr-1~deb12u1 | vulnerable |
| bookworm (security) | 128.12.0esr-1~deb12u1 | fixed |
| trixie | 128.11.0esr-1 | vulnerable |
| sid | 128.12.0esr-1 | fixed |
The information below is based on the following data on fixed versions.
Notes
https://www.mozilla.org/en-US/security/advisories/mfsa2025-51/#CVE-2025-6429
https://www.mozilla.org/en-US/security/advisories/mfsa2025-53/#CVE-2025-6429