CVE-2026-84641CWE-416

CVE-2026-84641

High · published September 2, 2026

CVSS v3.1
7.5
EPSS
0%
Percentile
17.9
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00267 · 17.9th percentile
Weakness
CWE-416 · Use After Free
Published
2026-09-02T02:17Z
Affected products (3)
ProductVersionsFixed in
mozilla/thunderbird< 140.15.0140.15.0
mozilla/thunderbird≥ 141.0, < 153.2.0153.2.0
mozilla/thunderbird≥ 154.0, < 155.0155.0
References (4)
https://bugzilla.mozilla.org/show_bug.cgi?id=2057805 · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-86/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-87/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-88/ · [email protected]
EPSS history
Timeline
  • 03 SEP 03:32Z
    EPSS moved — → 0%
    epss
  • 01 SEP 21:33Z
    Information disclosure due to malicious IMAP server response
    cvelistv5