CVE-2026-84641
Medium
Elevated severity or exploit probability.
CVSS base
7.5
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS — probability of exploitation (30 days)
0.3%
19.2th percentile
CISA KEV
Not listed
Weakness / dates
CWE-416
Published 2026-09-01 · modified 2026-09-03
CVSS breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
| Attack Vector | N | Network |
| Attack Complexity | L | Low |
| Privileges Required | N | None |
| User Interaction | N | None |
| Scope | U | Unchanged |
| Confidentiality | H | High |
| Integrity | N | None |
| Availability | N | None |
Timeline
- 2026-09-01 — Published (NVD)
- 2026-09-03 — Last modified (NVD)
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.