Vulnerability · Published Feb 6, 2026 · Assigned by GitHub_M
CVE-2026-25731Calibre Affected by Arbitrary Code Execution via Server-Side Template Injection in Calibre HTML Export
High 7.8
In plain English
A high-severity security flaw in calibre from kovidgoyal. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 20% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | calibre | 6.13.0+repack-2+deb12u6 | DEBIAN-CVE-2026-25731 |
| Debian:13 | calibre | 8.5.0+ds-1+deb13u2 | DEBIAN-CVE-2026-25731 |
| Debian:14 | calibre | 9.2.0+ds+~0.10.5-1 | DEBIAN-CVE-2026-25731 |
| Ubuntu:22.04:LTS | calibre | no fix listed | UBUNTU-CVE-2026-25731 |
| Ubuntu:24.04:LTS | calibre | no fix listed | UBUNTU-CVE-2026-25731 |
| Ubuntu:25.10 | calibre | no fix listed | UBUNTU-CVE-2026-25731 |
| Ubuntu:26.04:LTS | calibre | no fix listed | UBUNTU-CVE-2026-25731 |
| Ubuntu:26.10 | calibre | no fix listed | UBUNTU-CVE-2026-25731 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| kovidgoyal | calibre | < 9.2.0 |
Weakness: CWE-1336 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H