Bug 2437917 (CVE-2026-25731)

Summary: CVE-2026-25731 calibre: Calibre: Arbitrary Code Execution via malicious custom template file during ebook conversion
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Calibre, an e-book manager. This Server-Side Template Injection (SSTI) vulnerability in Calibre's Templite templating engine allows an attacker to achieve arbitrary code execution. This occurs when a user converts an ebook using a specially crafted malicious custom template file, provided via the --template-html or --template-html-index command-line options. This could lead to a complete compromise of the affected system.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2437953, 2437954    
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Description OSIDB Bzimport 2026-02-09 11:13:48 UTC
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.