Vulnerability in Mozilla Firefox
CVE-2026-12323
Spoofing issue in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 152 and Thunderbird 152.
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: 0.002 (5.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 5.5% 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 152
- Mozilla Thunderbird — versions 152
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2026-57/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-60/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-12323?
- CVE-2026-12323 is a medium-severity vulnerability in Mozilla Firefox, classified under Improper Restriction of Rendered UI Layers or Frames (Clickjacking). CVSS score: 5.4/10. Published 2026-06-16.
- How severe is CVE-2026-12323?
- Medium severity. CVSS v3 base score is 5.4 out of 10.