Critical severity9.8NVD Advisory· Published Sep 1, 2026· Updated Sep 3, 2026
CVE-2026-84143
CVE-2026-84143
Description
Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. 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 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
11- Range: 155, 140.15, 153.2
- Range: 154, 153.1, 140.14
- osv-coords9 versionspkg:apk/chainguard/firefox-docker-selenium-compatpkg:apk/wolfi/firefox-docker-selenium-compatpkg:rpm/almalinux/firefoxpkg:rpm/almalinux/firefox-x11pkg:rpm/almalinux/thunderbirdpkg:rpm/opensuse/MozillaFirefox&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/MozillaFirefox&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/MozillaThunderbird&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/firefox-esr&distro=openSUSE%20Tumbleweed
< 155.0.1-r0+ 8 more
- (no CPE)range: < 155.0.1-r0
- (no CPE)range: < 155.0.1-r0
- (no CPE)range: < 140.15.0-1.el10_2
- (no CPE)range: < 140.15.0-1.el9_8.alma.1
- (no CPE)range: < 140.16.0-1.el9_8.alma.1
- (no CPE)range: < 153.2.0-160000.1.1
- (no CPE)range: < 155.0-1.1
- (no CPE)range: < 140.15.0-1.1
- (no CPE)range: < 153.2.0-1.1
Patches
Vulnerability mechanics
References
9- www.mozilla.org/security/advisories/mfsa2026-82/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-84/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-85/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-86/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-87/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-88/nvdVendor Advisory
- bugzilla.mozilla.org/buglist.cginvdIssue Tracking
- bugzilla.mozilla.org/buglist.cginvdIssue Tracking
- bugzilla.mozilla.org/show_bug.cginvdIssue Tracking
News mentions
1- Mozilla Thunderbird: 16 Vulnerabilities Including Critical Sandbox Escapes Disclosed TogetherVypr Intelligence · Sep 1, 2026