Vulnerability in Mozilla Firefox
CVE-2025-8037
Setting a nameless cookie with an equals sign in the value shadowed other cookies. Even if the nameless cookie was set over HTTP and the shadowed cookie included the `Secure` attribute. This vulnerability was fixed in Firefox 141, Firefox ESR 140.1, Thunderbird 141, and Thunderbird 140.1.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (12.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 12.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
- Mozilla Firefox — versions 140.1, 141
- Mozilla Thunderbird — versions 140.1, 141
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2025-56/ (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/mfsa2025-63/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2025-8037?
- CVE-2025-8037 is a critical-severity vulnerability in Mozilla Firefox, classified under Sensitive Cookie in HTTPS Session Without 'Secure' Attribute. CVSS score: 9.1/10. Published 2025-07-22.
- How severe is CVE-2025-8037?
- Critical severity. CVSS v3 base score is 9.1 out of 10.