CVE-2026-73248

calibre: Bypass of Python template restrictions via nested `template()` leading to RCE

State: Published
Severity: 8.5 High
Published: Aug 11, 2026
Updated: Aug 12, 2026
Reserved: Aug 11, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
4.0	8.5 High	CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N	GitHub_M

Weaknesses

CWE-94 Improper Control of Generation of Code ('Code Injection')
CWE-95 Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')

Affected Products

Product	Versions
calibrekovidgoyal	< 9.12.0Affected

References

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