CVE-2026-73248: calibre: Bypass of Python template restrictions via nested `template()` leading to RCE

Published Aug 11, 2026
·
Updated

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

Affected Software

1 affected component
Calibre Calibre<9.12.0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade calibre to a version that resolves this vulnerability.

    Fixed in 9.12.0

Event History

Aug 11, 2026
CVE Published
via MITRE·09:56 PM
Data Sourced
via MITRE·09:56 PM
DescriptionWeakness
Data Sourced
via NVD·10:19 PM
DescriptionSeverityWeakness
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Frequently Asked Questions

1

What is the severity of CVE-2026-73248?

CVE-2026-73248 has a severity score of 80, indicating a high-risk vulnerability.

2

How do I fix CVE-2026-73248?

To fix CVE-2026-73248, upgrade to Calibre version 9.12.0 or later.

3

What type of vulnerability is CVE-2026-73248?

CVE-2026-73248 is classified as a Code Injection vulnerability.

4

What can an attacker do with CVE-2026-73248?

An attacker can exploit CVE-2026-73248 to execute remote code through the processing of malicious metadata in e-books.

5

Which versions of Calibre are affected by CVE-2026-73248?

CVE-2026-73248 affects all versions of Calibre prior to 9.12.0.

Company

Resources

Contact

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CVE-2026-73248 - calibre: Bypass of Python template restrictions via nested `template()` leading to RCE - SecAlerts