CVE-2025-6429mediumCWE-116

CVE-2025-6429: medium-severity vulnerability in Mozilla Firefox

Incorrect parsing of URLs could have allowed embedding of youtube.com

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13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 6.5epss 0.4%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Affected products
Mozilla · FirefoxMozilla · Thunderbird
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