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 products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| kovidgoyal | calibre | < 9.2.0 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | calibre | 9.2.0+ds+~0.10.5-1 | — |
| Debian 13 | calibre | 8.5.0+ds-1+deb13u2 | — |
| Debian 12 | calibre | 6.13.0+repack-2+deb12u6 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | calibre | No fix yet | — |
| Ubuntu 26.04 LTS | calibre | No fix yet | — |
| Ubuntu 25.10 | calibre | No fix yet | — |
| Ubuntu 24.04 LTS | calibre | No fix yet | — |
| Ubuntu 22.04 LTS | calibre | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | calibre | No fix yet | — |
| Ubuntu 18.04 LTS | calibre | No fix yet | — |
| Ubuntu 16.04 LTS | calibre | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | calibre | 9.7.0-1.1 | openSUSE-SU-2026:10587-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
GitHub 1 repository
-
dxlerYT/CVE-2026-25731 ★ 4 · Feb 6, 2026
Proof of Concept for a Server-Side Template Injection (SSTI) vulnerability in Calibre’s Templite engine (GHSA-xrh9-w7qx-3gcc). Demonstrates arbitrary Python code execution via user-supplied HTML expo…
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 1
- openSUSE-SU-2026:10587-1 calibre-9.7.0-1.1 on GA media SUSE / openSUSE Security Updates · Apr 22, 2026