CVE-2026-53511
Received Received - Intake

Arbitrary Code Execution in Calibre via Malicious EPUB Metadata

Publication date: 2026-07-07

Last updated on: 2026-07-07

Assigner: GitHub, Inc.

Description
calibre is an e-book manager. Prior to 9.10.0, a malicious EPUB, OPF, or PDF file can execute arbitrary Python code when its metadata is read by calibre, including through Add books or Edit books, by embedding a custom column definition with a python: template in calibre:user_metadata that is passed unsanitized to exec() in the template formatter. This issue is fixed in version 9.10.0.

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Meta Information

Published
2026-07-07
Last Modified
2026-07-07
Generated
2026-07-08
AI Q&A
2026-07-08
EPSS Evaluated
N/A
NVD
CVE-2026-53511

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
calibre calibre to 9.10.0 (exc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-94 The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

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Executive Summary

This vulnerability exists in calibre versions prior to 9.10.0, an e-book manager. A malicious EPUB, OPF, or PDF file can execute arbitrary Python code when its metadata is read by calibre. This happens because the file can embed a custom column definition using a python: template in calibre:user_metadata, which is passed unsanitized to the exec() function in the template formatter.

Impact Analysis

The vulnerability allows execution of arbitrary Python code with limited privileges when a malicious e-book file is processed by calibre. This can lead to unauthorized actions on the affected system, potentially compromising data integrity, confidentiality, or availability depending on the code executed.

Mitigation Strategies

To mitigate this vulnerability, upgrade calibre to version 9.10.0 or later, where the issue is fixed.

Avoid opening or importing EPUB, OPF, or PDF files from untrusted sources until the upgrade is applied.

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