Vulnerability · Published Jun 24, 2025 · Assigned by mozilla
CVE-2025-6429Incorrect parsing of URLs could have allowed embedding of youtube.com
Medium 6.5
In plain English
A medium-severity security flaw in Firefox from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 was fixed in Firefox 140, Firefox ESR 128.12, Thunderbird 140, and Thunderbird 128.12.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | firefox | 128.12.0-1.el10_0 | ALSA-2025:10073 |
| AlmaLinux:8 | firefox | 128.12.0-1.el8_10.alma.1 | ALSA-2025:10074 |
| AlmaLinux:9 | firefox | 128.12.0-1.el9_6.alma.1 | ALSA-2025:10072 |
| AlmaLinux:9 | firefox-x11 | 128.12.0-1.el9_6.alma.1 | ALSA-2025:10072 |
| AlmaLinux:8 | thunderbird | 128.12.0-1.el8_10.alma.1 | ALSA-2025:10246 |
| Debian:12 | firefox-esr | 128.12.0esr-1~deb12u1 | DEBIAN-CVE-2025-6429 |
| Debian:12 | firefox-esr | 128.12.0esr-1~deb12u1 | DSA-5950-1 |
| Debian:13 | firefox-esr | 128.12.0esr-1 | DEBIAN-CVE-2025-6429 |
| Debian:14 | firefox-esr | 128.12.0esr-1 | DEBIAN-CVE-2025-6429 |
| Debian:12 | thunderbird | 1:128.12.0esr-1~deb12u1 | DSA-5959-1 |
| Debian:12 | thunderbird | 1:128.12.0esr-1~deb12u1 | DEBIAN-CVE-2025-6429 |
| Debian:13 | thunderbird | 1:128.12.0esr-1 | DEBIAN-CVE-2025-6429 |
| Debian:14 | thunderbird | 1:128.12.0esr-1 | DEBIAN-CVE-2025-6429 |
| Rocky Linux:10 | firefox | 0:128.12.0-1.el10_0 | RLSA-2025:10073 |
| Rocky Linux:8 | firefox | 0:128.12.0-1.el8_10 | RLSA-2025:10074 |
| Rocky Linux:9 | firefox | 0:128.12.0-1.el9_6 | RLSA-2025:10072 |
| Rocky Linux:10 | thunderbird | 0:128.12.0-1.el10_0 | RLSA-2025:10195 |
| Rocky Linux:8 | thunderbird | 0:128.12.0-1.el8_10 | RLSA-2025:10246 |
| Rocky Linux:9 | thunderbird | 0:128.12.0-1.el9_6 | RLSA-2025:10196 |
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2025-6429 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2025-6429 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2025-6429 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2025-6429 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2025-6429 |
| Ubuntu:22.04:LTS | thunderbird | 1:128.12.0+build1-0ubuntu0.22.04.1 | UBUNTU-CVE-2025-6429 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | see references |
| Mozilla | Thunderbird | see references |
Weakness: CWE-116 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1970658
- https://www.mozilla.org/security/advisories/mfsa2025-51/
- https://www.mozilla.org/security/advisories/mfsa2025-53/
- https://www.mozilla.org/security/advisories/mfsa2025-54/
- https://www.mozilla.org/security/advisories/mfsa2025-55/
- https://lists.debian.org/debian-lts-announce/2025/07/msg00002.html
- https://lists.debian.org/debian-lts-announce/2025/06/msg00029.html