Cyber Resilience

CVE-2026-25731

Calibre-Ebook Calibre ≤ 9.2.0

Public PoC
Published
06 February 2026
Modified
17 February 2026
Patch / advisory
View advisory
CVSS Score v3.1 7.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.0024 15th percentile
Risk Priority 56 floored blend · peak EPSS

Summary

CVE-2026-25731 is a high-severity Improper Neutralization of Special Elements Used in a Template Engine (CWE-1336) vulnerability in Calibre-Ebook Calibre. Its CVSS base score is 7.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Template Injection (T1221); ranked at the 15th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-25731 is a Server-Side Template Injection (SSTI) vulnerability (CWE-1336) in the Templite templating engine used by Calibre, an open-source e-book manager. The issue affects versions of Calibre prior to 9.2.0 and enables arbitrary code execution when a user processes an e-book using a malicious custom template file supplied via the --template-html or --template-html-index command-line options during conversion.

The vulnerability requires local access (AV:L) with low attack complexity (AC:L), no privileges (PR:N), and user interaction (UI:R), as scored at CVSS 7.8 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H). A local attacker can exploit it by tricking a user into converting a specially crafted e-book that includes a malicious template, leading to arbitrary code execution on the victim's machine with high impacts on confidentiality, integrity, and availability.

Calibre's security advisory (GHSA-xrh9-w7qx-3gcc) and the fixing commit (f0649b27512e987b95fcab2e1e0a3bcdafc23379) confirm the vulnerability was patched in version 9.2.0, recommending users update to this release to mitigate the issue.

EU & UK References

Vulnerability Data

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…

more

command-line options. This vulnerability is fixed in 9.2.0.

CWE(s)
CWE-1336

Related Threats

MITRE ATT&CK Enterprise Techniques

T1221 Template Injection Stealth
Adversaries may create or modify references in user document templates to conceal malicious code or force authentication attempts.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-26065Same product: Calibre-Ebook Calibre
CVE-2023-46303Same product: Calibre-Ebook Calibre
CVE-2026-27810Same product: Calibre-Ebook Calibre
CVE-2026-25636Same product: Calibre-Ebook Calibre
CVE-2026-27824Same product: Calibre-Ebook Calibre
CVE-2026-33205Same product: Calibre-Ebook Calibre
CVE-2026-26064Same product: Calibre-Ebook Calibre
CVE-2024-6781Same product: Calibre-Ebook Calibre
CVE-2024-7009Same product: Calibre-Ebook Calibre
CVE-2026-25635Same product: Calibre-Ebook Calibre

Affected Assets

calibre-ebook
calibre
≤ 9.2.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.3.2
  • V1.3.7
  • V1.3.10

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and static analysis can discover missing neutralization of template directives.

SI-10 Information Input Validation good match

Input validation rejects or sanitizes untrusted data before it reaches the template engine, stopping injection of special syntax.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles require use of safe templating APIs and proper escaping of external input.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require proper input neutralization in template engines to prevent injection.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect template-injection flaws but does not itself implement neutralization controls.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation and sanitization that directly prevents template-injection weaknesses.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for neutralizing special elements in template engines.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles reduce the likelihood of unsafe template processing but do not prescribe specific neutralization techniques.

A.8.28 Secure coding partial match
prevents

Secure coding standards require proper escaping or sandboxing of template directives, directly mitigating CWE-1336.

References