CVE-2026-53511: calibre: Arbitrary Code Execution in Template Formatter via Book Metadata

Severity: high (CVSS 8.5 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-07 · updated 2026-10-25
Weakness: CWE-94

Description

calibre is an e-book manager. Prior to 9.10.0, a malicious EPUB, OPF, or PDF file can execute arbitrary Python code when its metadata is read by calibre, including through Add books or Edit books, by embedding a custom column definition with a python: template in calibre:user_metadata that is passed unsanitized to exec() in the template formatter. This issue is fixed in version 9.10.0.

Affected products

kovidgoyal calibre: before 9.10.0

References

https://github.com/kovidgoyal/calibre/commit/712f4e1ff5c1e798c335bef3bacc4efdee052e9c
https://github.com/kovidgoyal/calibre/releases/tag/v9.10.0
https://github.com/kovidgoyal/calibre/security/advisories/GHSA-2j4m-2q7x-2c47
https://lists.debian.org/debian-lts-announce/2026/08/msg00034.html
https://github.com/kovidgoyal/calibre/security/advisories/GHSA-2j4m-2q7x-2c47

Get alerted when CVE-2026-53511 or the next vulnerability affects your stack