CVE-2026-74988
Internally found bugs fixed in Thunderbird ESR 153.1 and Thunderbird 154
CVSS Score
9.8
EPSS Score
0.4%
EPSS Percentile
28th
Internally found bugs present in Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
| Vendor | mozilla |
| Product | firefox |
| Ecosystems | |
| Industries | Technology |
| Published | Aug 18, 2026 |
| Last Updated | Sep 1, 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=2018164%2C2045404%2C2045507%2C2045711%2C2052403%2C2053174%2C2054643%2C2054667%2C2054671%2C2054674%2C2054687%2C2054717%2C2054761%2C2054787%2C2055676%2C2056779%2C2056781%2C2058629%2C2059019%2C2059138 bugzilla.mozilla.org: https://bugzilla.mozilla.org/buglist.cgi?bug_id=2045796%2C2046734%2C2051424%2C2054721%2C2057994%2C2058094%2C2058611%2C2058615%2C2058616%2C2061315 bugzilla.mozilla.org: https://bugzilla.mozilla.org/buglist.cgi?bug_id=2053153%2C2053262%2C2054763%2C2059198%2C2059224 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-74/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-77/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-78/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-80/
Credits
Gabriele Svelto, Tom Ritter, Tom Schuster and the Mozilla Fuzzing Team