CVE-2026-25731

Calibre Affected by Arbitrary Code Execution via Server-Side Template Injection in Calibre HTML Export

7.8 HighPublic exploitFix available

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.

Attack profile

How easy it is to exploit

Attack vector: Local
Complexity: Low
Privileges needed: None
User interaction: Required

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

0.28%Up 0.3 points since Feb 7, 2026

What each source reports

CVE List Score used 7.8

Calibre Affected by Arbitrary Code Execution via Server-Side Template Injection in Calibre HTML Export

Record: CVE-2026-25731
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness: CWE-1336
Updated: 2026-11-02

EUVDEUVD-2026-5573 7.8

Record: EUVD-2026-5573
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated: 2026-11-02

NVD 7.8

Record: CVE-2026-25731
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness: CWE-1336
Updated: 2026-11-02

OSV 7.8

Calibre Affected by Arbitrary Code Execution via Server-Side Template Injection in Calibre HTML Export

Record: CVE-2026-25731
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness: CWE-1336
Updated: 2026-11-02

OSVDEBIAN-CVE-2026-25731 7.8

Record: DEBIAN-CVE-2026-25731
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVUBUNTU-CVE-2026-25731 7.8

Record: UBUNTU-CVE-2026-25731
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVopenSUSE-SU-2026:10587-1 No score

calibre-9.7.0-1.1 on GA media

These are all security issues fixed in the calibre-9.7.0-1.1 package on the GA media of openSUSE Tumbleweed.

Record: openSUSE-SU-2026:10587-1
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`calibre` Debian:12	before 6.13.0+repack-2+deb12u6, plus listed versions 6.13.0+repack-26.13.0+repack-2+deb12u16.13.0+repack-2+deb12u26.13.0+repack-2+deb12u36.13.0+repack-2+deb12u46.13.0+repack-2+deb12u5	6.13.0+repack-2+deb12u6
`calibre` Debian:13	before 8.5.0+ds-1+deb13u2, plus listed versions 8.5.0+ds-18.5.0+ds-1+deb13u1	8.5.0+ds-1+deb13u2
`calibre` Debian:14	before 9.2.0+ds+~0.10.5-1, plus listed versions 8.10.0+ds-18.10.0+ds-28.10.0+ds-38.11.0+ds+~0.10.5-18.11.1+ds+~0.10.5-1 Show 31 moreShow less 8.11.1+ds+~0.10.5-28.11.1+ds+~0.10.5-38.12.0+ds+~0.10.5-18.13.0+ds+~0.10.5-18.13.0+ds+~0.10.5-28.13.0+ds+~0.10.5-38.14.0+ds+~0.10.5-18.14.0+ds+~0.10.5-1~bpo13+18.15.0+ds+~0.10.5-18.15.0+ds+~0.10.5-1~bpo13+18.15.0+ds+~0.10.5-28.16.0+ds+~0.10.5-18.16.0+ds+~0.10.5-28.16.1+ds+~0.10.5-18.16.2+ds+~0.10.5-18.16.2+ds+~0.10.5-28.16.2+ds+~0.10.5-38.16.2+ds+~0.10.5-3~bpo13+18.5.0+ds-18.6.0+ds-18.7.0+ds-18.8.0+ds-18.8.0+ds-28.8.0+ds-2+gcc158.8.0+ds-38.9.0+ds-18.9.0+ds-28.9.0+ds-38.9.0+ds-49.0.0+ds+~0.10.5-19.1.0+ds+~0.10.5-1	9.2.0+ds+~0.10.5-1
`calibre` Ubuntu:16.04:LTS	All versions, plus listed versions 2.33.0+dfsg-1build12.38.0+dfsg-12.45.0+dfsg-12.45.0+dfsg-1build12.48.0+dfsg-1 Show 4 moreShow less 2.48.0+dfsg-1build12.54.0+dfsg-12.55.0+dfsg-12.55.0+dfsg-1ubuntu0.2	None known
`calibre` Ubuntu:18.04:LTS	All versions, plus listed versions 3.7.0+dfsg-23.7.0+dfsg-2build13.12.0+dfsg-13.13.0+dfsg-13.14.0+dfsg-1 Show 10 moreShow less 3.15.0.1+dfsg-13.16.0+dfsg-13.16.0+dfsg-1build13.17.0+dfsg-13.17.0+dfsg-23.18.0+dfsg-1build13.19.0+dfsg-13.20.0+dfsg-13.21.0+dfsg-13.21.0+dfsg-1build1	None known
`calibre` Ubuntu:20.04:LTS	All versions, plus listed versions 3.46.0+dfsg-14.2.0+dfsg-24.3.0+dfsg-14.3.0+dfsg-24.4.0+dfsg-1 Show 14 moreShow less 4.5.0+dfsg-14.5.0+dfsg-24.5.0+dfsg-34.6.0+dfsg-14.7.0+dfsg-14.99.3+dfsg-24.99.4+dfsg-14.99.4+dfsg-1build14.99.4+dfsg+really4.10.0+py3-24.99.4+dfsg+really4.11.2-14.99.4+dfsg+really4.11.2-1build14.99.4+dfsg+really4.12.0-14.99.4+dfsg+really4.12.0-1build14.99.4+dfsg+really4.12.0-1ubuntu1	None known
`calibre` Ubuntu:22.04:LTS	All versions, plus listed versions 5.25.0+dfsg-25.33.2+dfsg-15.34.0+dfsg-15.35.0+dfsg-1ubuntu25.37.0+dfsg-15.37.0+dfsg-1build1	None known
`calibre` Ubuntu:24.04:LTS	All versions, plus listed versions 6.24.0+ds-16.29.0+ds-17.0.0+ds-17.1.0+ds-17.1.0+ds-2 Show 9 moreShow less 7.2.0+ds-17.2.0+ds-1build17.3.0+ds-17.4.0+ds-17.5.1+ds-17.5.1+ds-27.5.1+ds-37.6.0+ds-17.6.0+ds-1build1	None known
`calibre` Ubuntu:25.10	All versions, plus listed versions 7.26.0+ds-4build18.3.0+ds-18.4.0+ds-18.5.0+ds-18.6.0+ds-1 Show 4 moreShow less 8.7.0+ds-18.8.0+ds-28.8.0+ds-38.8.0+ds-3build1	None known
`calibre` Ubuntu:26.10	All versions, plus listed versions 9.2.1+ds+~0.10.5-2build19.9.0+ds+~0.10.6-19.11.0+ds+~0.10.6-19.11.0+ds+~0.10.6-29.13.0+ds+~0.10.6-19.14.0+ds+~0.10.6-2build1	None known
`calibre` Ubuntu:26.04:LTS	All versions, plus listed versions 8.8.0+ds-3build18.13.0+ds+~0.10.5-38.14.0+ds+~0.10.5-18.15.0+ds+~0.10.5-18.16.0+ds+~0.10.5-2 Show 4 moreShow less 8.16.2+ds+~0.10.5-18.16.2+ds+~0.10.5-28.16.2+ds+~0.10.5-39.2.1+ds+~0.10.5-2build1	None known
`calibre` openSUSE:Tumbleweed From an advisory covering 10 CVEs	before 9.7.0-1.1	9.7.0-1.1

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
Source	Link	Date
PoC in GitHub	dxlerYT/CVE-2026-25731	2026-02-06

History

History
Recorded	Changed	Sources
Nov 6, 2026	affected, facts
Nov 2, 2026	first indexed	CVE List, EUVD, NVD, OSV, PoC in GitHub

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-25731 is a high vulnerability (CVSS 7.8) in Calibre-ebook Calibre, published February 6, 2026. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 0.28%, the 20th percentile. Fixed in calibre 6.13.0+repack-2+deb12u6.

References

Show 11 moreShow less