CVE-2025-6429: Vulnerability in Mozilla Firefox
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.
AI Analysis
Technical Summary
This vulnerability involves Firefox incorrectly parsing a URL specified in an embed tag and rewriting it to the youtube.com domain. This behavior could bypass website security policies that restrict embedding to certain domains. The flaw was addressed and fixed in Firefox 140 and Firefox ESR 128.12. The CVSS score is 6.5 (medium severity) with an impact primarily on integrity due to the potential bypass of domain restrictions. The vulnerability is tracked as CWE-116 (Improper Encoding or Escaping of Output).
Potential Impact
An attacker could exploit this vulnerability to embed content from youtube.com even if the website's security policy restricts embedding to other domains. This could lead to unintended content being displayed, potentially undermining site security controls. There is no indication of direct confidentiality or availability impact. No known exploits in the wild have been reported.
Mitigation Recommendations
This vulnerability has been fixed in Firefox 140 and Firefox ESR 128.12. Users and administrators should update to these versions or later to remediate this issue. Since this is a client-side browser vulnerability, applying the official Mozilla updates fully mitigates the risk.
CVE-2025-6429: Vulnerability in Mozilla Firefox
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves Firefox incorrectly parsing a URL specified in an embed tag and rewriting it to the youtube.com domain. This behavior could bypass website security policies that restrict embedding to certain domains. The flaw was addressed and fixed in Firefox 140 and Firefox ESR 128.12. The CVSS score is 6.5 (medium severity) with an impact primarily on integrity due to the potential bypass of domain restrictions. The vulnerability is tracked as CWE-116 (Improper Encoding or Escaping of Output).
Potential Impact
An attacker could exploit this vulnerability to embed content from youtube.com even if the website's security policy restricts embedding to other domains. This could lead to unintended content being displayed, potentially undermining site security controls. There is no indication of direct confidentiality or availability impact. No known exploits in the wild have been reported.
Mitigation Recommendations
This vulnerability has been fixed in Firefox 140 and Firefox ESR 128.12. Users and administrators should update to these versions or later to remediate this issue. Since this is a client-side browser vulnerability, applying the official Mozilla updates fully mitigates the risk.
Technical Details
- Data Version
- 5.1
- Assigner Short Name
- mozilla
- Date Reserved
- 2025-06-20T14:51:34.184Z
- Cvss Version
- null
- State
- PUBLISHED
Threat ID: 685aa0274dc24046c1dc5aa4
Added to database: 6/24/2025, 12:55:03 PM
Last enriched: 4/14/2026, 11:51:53 AM
Last updated: 5/9/2026, 12:42:08 AM
Views: 77
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