CVE-2026-25731: Calibre Affected by Arbitrary Code Execution via Server-Side Template Injection in Calibre HTML Export

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-02-06 · updated 2026-06-17
Weakness: CWE-1336

Description

calibre is an e-book manager. Prior to 9.2.0, a Server-Side Template Injection (SSTI) vulnerability in Calibre's Templite templating engine allows arbitrary code execution when a user converts an ebook using a malicious custom template file via the --template-html or --template-html-index command-line options. This vulnerability is fixed in 9.2.0.

Affected products

kovidgoyal calibre: before 9.2.0 — fixed in 9.2.0

How to fix

Upgrade to a fixed version: kovidgoyal calibre 9.2.0. Check the vendor advisory for mitigations.

References

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