CVE-2025-8031
Published: 22 July 2025
Summary
CVE-2025-8031 is a critical-severity Incorrect Default Permissions (CWE-276) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Unsecured Credentials (T1552); ranked at the 34.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and RA-5 (Vulnerability Monitoring and Scanning).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
SI-2 mandates identifying, prioritizing, and applying patches for critical flaws like CVE-2025-8031 to prevent HTTP Basic Authentication credential leakage in CSP reports.
SI-5 requires reviewing and acting on vendor security advisories such as Mozilla's MFSA to promptly update Firefox and Thunderbird against CVE-2025-8031.
RA-5 enables vulnerability scanning to identify systems running vulnerable versions of Firefox or Thunderbird affected by CVE-2025-8031.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vulnerability directly causes HTTP Basic Auth credentials to be included unredacted in CSP violation reports sent to attacker-controlled endpoints, enabling credential exposure/leakage.
NVD Description
The `username:password` part was not correctly stripped from URLs in CSP reports potentially leaking HTTP Basic Authentication credentials. This vulnerability was fixed in Firefox 141, Firefox ESR 128.13, Firefox ESR 140.1, Thunderbird 141, Thunderbird 128.13, and Thunderbird 140.1.
Deeper analysisAI
CVE-2025-8031 is a vulnerability in Mozilla Firefox and Thunderbird where the `username:password` component of URLs was not properly stripped from Content Security Policy (CSP) reports, potentially exposing HTTP Basic Authentication credentials. This issue, classified under CWE-276 (Incorrect Default Permissions), affects versions of Firefox prior to 141, Firefox ESR prior to 128.13 and 140.1, Thunderbird prior to 141, and Thunderbird ESR prior to 128.13 and 140.1. The vulnerability carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating critical severity due to its high impact on confidentiality, integrity, and availability.
A remote attacker can exploit this vulnerability over the network with low complexity, requiring no privileges or user interaction. By triggering a CSP violation on a page protected by HTTP Basic Authentication, the attacker can cause the browser to send a CSP report containing the unredacted URL with embedded credentials to a report endpoint under the attacker's control, leading to credential leakage. This enables unauthorized access to protected resources, potentially resulting in high-impact compromises.
Mozilla's security advisories (MFSA 2025-56, 58, 59, and 61) and the associated Bugzilla entry detail the fix implemented in the listed versions, recommending immediate updates to Firefox 141, Firefox ESR 128.13 or 140.1, Thunderbird 141, or Thunderbird ESR 128.13 or 140.1 as the primary mitigation. No workarounds are specified beyond applying the patches.
Details
- CWE(s)