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VulnerabilityPublished

CVE-2026-25731: kovidgoyal calibre · Template Injection

Affects kovidgoyal calibreSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High : upgrade to 9.2.0 soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 9.2.0
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 6 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade calibre and kovidgoyal/calibre to 9.2.0.

Affected software

ProductAffectedFixed in
kovidgoyalcalibreAffected
  • <9.2.0
Fixed in
  • 9.2.0
GitHubkovidgoyal/calibrepkg:github/kovidgoyal/calibreOther threatsAffected
  • <9.2.0
Fixed in
  • 9.2.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

The primary mitigation is to upgrade all calibre installations to version 9.2.0 or later, where the vulnerability is patched. Organizations should audit their usage of the --template-html and --template-html-index options to ensure that only trusted templates are used. Restrict access to systems running calibre to trusted personnel and enforce strict user permissions to prevent unauthorized template injection. Implement monitoring and alerting for unusual or unauthorized execution of calibre conversion commands, especially those involving custom templates. In environments where calibre is integrated into automated workflows, validate and sanitize all template inputs before processing. Consider isolating calibre execution in sandboxed or containerized environments to limit potential damage from exploitation. Finally, educate users about the risks of running calibre with untrusted templates and enforce policies to avoid such practices.

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.

References

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