URL Leakage Vulnerability in Firefox and Thunderbird by Mozilla
CVE-2025-8031

9.8CRITICAL

Key Information:

Vendor

Mozilla
Status
Firefox
Firefox Esr
Thunderbird
Vendor
CVE Published:
22 July 2025

What is CVE-2025-8031?

This vulnerability arises when the username:password section is not properly removed from URLs within Content Security Policy (CSP) reports. As a result, it can inadvertently expose users' HTTP Basic Authentication credentials. This issue affects specific versions of Firefox and Thunderbird, potentially leading to unauthorized access to sensitive information transmitted via these applications. Users are encouraged to update to the latest versions to mitigate this risk.

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Affected Version(s)

Firefox < 141

Firefox ESR < 128.13

Firefox ESR < 140.1

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1971719
https://www.mozilla.org/security/advisories/mfsa2025-56/
https://www.mozilla.org/security/advisories/mfsa2025-58/

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

Tom Schuster
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