KMail since version 5.3.0 used a QWebEngine based viewer that had JavaScript enabled. HTML Mail contents were not sanitized for JavaScript and included code was executed.
Severity
CVSS 3.0
6.5 medium
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
EPSS
1.2% chance of exploitation in the next 30 days; higher than 67% of CVEs (scores of 2026-10-31)