// For flags

CVE-2025-6429

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

Severity Score

6.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

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.

A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue: 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.

*Credits: Masato Kinugawa
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
None
Integrity
Complete
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2025-06-20 CVE Reserved
  • 2025-06-24 CVE Published
  • 2025-06-25 CVE Updated
  • 2025-06-30 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-116: Improper Encoding or Escaping of Output
  • CWE-706: Use of Incorrectly-Resolved Name or Reference
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Mozilla
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Firefox
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*-
Affected
Mozilla
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Firefox Esr
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*-
Affected
Debian
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Debian Linux
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*-
Affected
Fedoraproject
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Fedora
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*-
Affected
Opensuse
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Leap
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*-
Affected
Slackware
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Slackware Linux
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*-
Affected
Suse
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Sle-module-desktop-applications
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*-
Affected
Suse
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Sle Hpc-espos
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Affected
Suse
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Sle Hpc-ltss
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Affected
Suse
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Sle Hpc
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*-
Affected
Suse
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Sled
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Affected
Suse
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Sles-ltss-extended-security
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Affected
Suse
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Sles-ltss
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Affected
Suse
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Sles
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Affected
Suse
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Sles Sap
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Affected