Vulnerability in Mozilla Firefox
CVE-2025-8031
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (37.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 37.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.000
Affected products
- Mozilla Firefox — versions 128.13, 140.1, 141
- Mozilla Thunderbird — versions 128.13, 140.1, 141
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2025-56/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-58/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-59/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-61/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-62/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-63/ (Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-8031?
- CVE-2025-8031 is a critical-severity vulnerability in Mozilla Firefox, classified under Incorrect Default Permissions. CVSS score: 9.8/10. Published 2025-07-22.
- How severe is CVE-2025-8031?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2025-8031 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.