CVE-2026-73248: Kovidgoyal Calibre

High severity, CVSS 8.5. EPSS: 0.2% chance of exploitation in the next 30 days.

calibre is an e-book manager. Prior to 9.12.0, calibre processes attacker-controlled composite_template metadata from a malicious EPUB, OPF, PDF, or similar file through program: and a nested template() call whose formatter does not inherit allow_python_templates=False, allowing a nested python: template to reach compile_python_template and execute arbitrary Python code when the file is opened or imported. This issue is fixed in version 9.12.0.

Affected products

• Kovidgoyal Calibre: before 9.12.0 (fixed in 9.12.0)

Published 2026-08-11. Last modified 2026-09-09.