CVE-2026-4729
Memory safety bugs fixed in Firefox 149 and Thunderbird 149
CVSS Score
9.8
EPSS Score
0.0%
EPSS Percentile
0th
Memory safety bugs present in Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149 and Thunderbird 149.
| Vendor | mozilla |
| Product | firefox |
| Ecosystems | |
| Industries | Technology |
| Published | Mar 24, 2026 |
| Last Updated | Jul 15, 2026 |
Stay Ahead of the Next One
Get instant alerts for mozilla firefox
Be the first to know when new critical vulnerabilities affecting mozilla firefox are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
Affected Versions
Mozilla / Firefox
All versions affected Mozilla / Thunderbird
All versions affected References
bugzilla.mozilla.org: https://bugzilla.mozilla.org/buglist.cgi?bug_id=1944033%2C1997282%2C2009213%2C2011412%2C2021925%2C2022034 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-20/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-23/ access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-4729 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2450745 security.access.redhat.com: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4729.json
Credits
Christian Holler, Fatih Kilic, Tom Schuster and the Mozilla Fuzzing Team