Vulnerability in Mozilla Firefox
CVE-2026-0890
Spoofing issue in the DOM: Copy & Paste and Drag & Drop component. This vulnerability was fixed in Firefox 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L.
EPSS exploit prediction
EPSS: 0.003 (20.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 20.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000
Affected products
- Mozilla Firefox — versions 140.7, 147
- Mozilla Thunderbird — versions 140.7, 147
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2026-01/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-03/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-04/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-05/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-0890?
- CVE-2026-0890 is a medium-severity vulnerability in Mozilla Firefox, classified under Authentication Bypass by Spoofing. CVSS score: 5.4/10. Published 2026-01-13.
- How severe is CVE-2026-0890?
- Medium severity. CVSS v3 base score is 5.4 out of 10.