Medium (5.9) in mozilla thunderbird. EPSS 1.2% chance of exploitation in the next 30 days.
If Thunderbird was configured to use STARTTLS for an IMAP connection, and an attacker injected IMAP server responses prior to the completion of the STARTTLS handshake, then Thunderbird didn't ignore the injected data. This could have resulted in Thunderbird showing incorrect information, for example the attacker could have tricked Thunderbird to show folders that didn't exist on the IMAP server. This vulnerability affects Thunderbird < 78.12.
Severity
CVSS 3.1
5.9 medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
1.2% chance of exploitation in the next 30 days; higher than 68% of CVEs (scores of 2026-10-31)