CVE-2026-92240
A malicious or compromised IMAP server can trigger an out-of-bounds read in the IMAP response parser by sending an untagged '* ID' response, crashing Thunderbird. The affected parsing path is reachable before authentication. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.
- Published Sep 15, 2026
- CVSS 9.1 critical
- 0.6% chance of exploitation in the next 30 days (EPSS)
- A fix is available