URL Truncation Vulnerability in Firefox and Thunderbird by Mozilla
CVE-2025-8043

9.8CRITICAL

Key Information:

Vendor

Mozilla
Status
Firefox
Thunderbird
Vendor
CVE Published:
22 July 2025

What is CVE-2025-8043?

This vulnerability arises from the incorrect truncation of URLs in Firefox and Thunderbird, where URLs are truncated at the beginning instead of around the origin. This flaw potentially exposes users to unexpected behavior and security risks, emphasizing the importance of updating to the latest versions.

Affected Version(s)

Firefox < 141

Thunderbird < 141

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1970209
https://www.mozilla.org/security/advisories/mfsa2025-56/
https://www.mozilla.org/security/advisories/mfsa2025-61/

CVSS V3.1

Score:
9.8
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

alayersattackers
.
CVE-2025-8043 : URL Truncation Vulnerability in Firefox and Thunderbird by Mozilla