High severity7.5NVD Advisory· Published Sep 1, 2026· Updated Sep 3, 2026
CVE-2026-84641
CVE-2026-84641
Description
A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID response. Heap contents can ultimately be persisted to prefs.js. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Affected products
3- Range: before 155, before 140.15, before 153.2
- osv-coords2 versions
< 140.15.0-1.1+ 1 more
- (no CPE)range: < 140.15.0-1.1
- (no CPE)range: < 140.16.0-1.el9_8.alma.1
Patches
Vulnerability mechanics
References
4- 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/show_bug.cginvdPermissions Required
News mentions
1- Mozilla Thunderbird: 16 Vulnerabilities Including Critical Sandbox Escapes Disclosed TogetherVypr Intelligence · Sep 1, 2026