CVE-2025-6429
Published: 24 June 2025
Summary
CVE-2025-6429 is a medium-severity Improper Encoding or Escaping of Output (CWE-116) vulnerability in Mozilla Firefox. Its CVSS base score is 6.5 (Medium).
Operationally, ranked in the top 36.9% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-21378
Vulnerability details
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…
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vulnerability was fixed in Firefox 140, Firefox ESR 128.12, Thunderbird 140, and Thunderbird 128.12.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Validating that output matches expected content directly mitigates failures to properly encode or escape data for its destination context.