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.
https://github.com/kovidgoyal/calibre/security/advisories/GHSA-2j4m-2q7x-2c47
https://github.com/kovidgoyal/calibre/releases/tag/v9.10.0
https://github.com/kovidgoyal/calibre/commit/712f4e1ff5c1e798c335bef3bacc4efdee052e9c
Published: 2026-07-07
Updated: 2026-07-07
Base Score: 6.8
Vector: CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:P
Severity: Medium
Base Score: 9.8
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: Critical
Base Score: 8.5
Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Severity: High