CVE-2025-6429

6.5 MEDIUM
Published: June 24, 2025 Modified: November 03, 2025

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1970658
Source: security@mozilla.org
Permissions Required
https://www.mozilla.org/security/advisories/mfsa2025-51/
Source: security@mozilla.org
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-53/
Source: security@mozilla.org
Vendor Advisory

7 reference(s) from NVD

Quick Stats

CVSS v3 Score
6.5 / 10.0
EPSS (Exploit Probability)
0.1%
18th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

mozilla