High severity · published Aug 11, 2026
CVE-2026-73248
calibre: Bypass of Python template restrictions via nested `template()` leading to RCE
8.5
CVSS
0.2%
EPSS
No
On KEV
Description
calibre is an e-book manager. Prior to 9.12.0, calibre processes attacker-controlled composite_template metadata from a malicious EPUB, OPF, PDF, or similar file through program: and a nested template() call whose formatter does not inherit allow_python_templates=False, allowing a nested python: template to reach compile_python_template and execute arbitrary Python code when the file is opened or imported. This issue is fixed in version 9.12.0.
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 9% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CA
calibre · kovidgoyal
< 9.12.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-73248
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-73248
github.com
https://github.com/kovidgoyal/calibre/commit/dac9990458374a81a5372a768bba6527d965aac8
github.com
https://github.com/kovidgoyal/calibre/releases/tag/v9.12.0
github.com
https://github.com/kovidgoyal/calibre/security/advisories/GHSA-4f7g-rjfp-hmvx
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