Vulnerability in Mozilla Firefox
CVE-2026-74984
Race condition in the JavaScript Engine component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
Vulnerability class: Race Condition
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.003 (18.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 18.3% 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: 0.003 · change: +0.001
Affected products
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2026-74/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-77/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-78/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-80/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-74984?
- CVE-2026-74984 is a medium-severity vulnerability in Mozilla Firefox, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 6.8/10. Published 2026-08-18.
- How severe is CVE-2026-74984?
- Medium severity. CVSS v3 base score is 6.8 out of 10.