Critical severity9.8NVD Advisory· Published Aug 18, 2026· Updated Sep 1, 2026
CVE-2026-74987
CVE-2026-74987
Description
Internally found bugs present in Thunderbird ESR 140.13, 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 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
11- osv-coords10 versionspkg:rpm/almalinux/firefoxpkg:rpm/opensuse/MozillaFirefox&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/MozillaFirefox&distro=openSUSE%20Tumbleweedpkg:rpm/almalinux/thunderbirdpkg:rpm/almalinux/firefox-x11pkg:rpm/opensuse/firefox-esr&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/MozillaThunderbird&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/mozilla-nspr&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/mozilla-nss&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/rust-cbindgen&distro=openSUSE%20Leap%2016.0
< 140.14.0-1.el9_8.alma.1+ 9 more
- (no CPE)range: < 140.14.0-1.el9_8.alma.1
- (no CPE)range: < 140.14.0-160000.1.1
- (no CPE)range: < 154.0-1.1
- (no CPE)range: < 140.14.0-1.el9_8.alma.1
- (no CPE)range: < 140.14.0-1.el9_8.alma.1
- (no CPE)range: < 153.1.0-1.1
- (no CPE)range: < 140.14.0-1.1
- (no CPE)range: < 4.39-160000.1.1
- (no CPE)range: < 3.125-160000.1.1
- (no CPE)range: < 0.29.4+git0-160000.1.1
- Range: 140.13, 153.0
Patches
Vulnerability mechanics
References
9- www.mozilla.org/security/advisories/mfsa2026-74/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-76/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-77/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-78/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-79/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-80/nvdVendor Advisory
- bugzilla.mozilla.org/buglist.cginvdBroken Link
- bugzilla.mozilla.org/buglist.cginvdBroken Link
- bugzilla.mozilla.org/show_bug.cginvdPermissions Required
News mentions
1- Mozilla Thunderbird: 25 Vulnerabilities Disclosed, Ranging from Critical to Medium SeverityVypr Intelligence · Aug 18, 2026