CVE-2026-73248

calibre: Bypass of Python template restrictions via nested `template()` leading to RCE

8.5 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector: Local
Complexity: Low
Privileges needed: None
User interaction: Passive

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

0.20%Unchanged since Aug 12, 2026

What each source reports

CVE List Score used 8.5

calibre: Bypass of Python template restrictions via nested `template()` leading to RCE

Record: CVE-2026-73248
CVSS 4.0: 8.5 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness: CWE-94, CWE-95
Updated: 2026-11-02

EUVDEUVD-2026-57014 8.5

Record: EUVD-2026-57014
CVSS 4.0: 8.5 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated: 2026-11-02

NVD 8.5

Record: CVE-2026-73248
CVSS 4.0: 8.5 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness: CWE-94, CWE-95
Updated: 2026-11-02

OSV 8.5

calibre: Bypass of Python template restrictions via nested `template()` leading to RCE

Record: CVE-2026-73248
CVSS 4.0: 8.5 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness: CWE-94, CWE-95
Updated: 2026-11-02

OSVDEBIAN-CVE-2026-73248 8.5

Record: DEBIAN-CVE-2026-73248
CVSS 4.0: 8.5 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated: 2026-11-02

OSVUBUNTU-CVE-2026-73248 8.5

Record: UBUNTU-CVE-2026-73248
CVSS 4.0: 8.5 HighCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated: 2026-11-02

Affected products

kovidgoyal calibre

Affected packages

Affected packages
Package	Affected	Fixed
`calibre` Debian:12	All versions, plus listed versions 6.13.0+repack-26.13.0+repack-2+deb12u16.13.0+repack-2+deb12u106.13.0+repack-2+deb12u26.13.0+repack-2+deb12u3 Show 45 moreShow less 6.13.0+repack-2+deb12u46.13.0+repack-2+deb12u56.13.0+repack-2+deb12u66.13.0+repack-2+deb12u76.13.0+repack-2+deb12u86.13.0+repack-2+deb12u96.14.0-16.14.1-16.15.0-16.15.1-16.15.1-26.15.1-36.15.1-46.16.0-16.17.0-16.18.1-16.18.1-26.18.1-36.19.1-16.20.0-16.21.0-16.21.0-26.22.0-16.23.0-16.23.0-26.24.0+ds-16.24.0-16.24.0-26.25.0+ds-16.26.0+ds-16.27.0+ds-16.28.0+ds-16.28.1+ds-16.29.0+ds-17.0.0+ds-17.1.0+ds-17.1.0+ds-27.10.0+ds-17.11.0+ds-17.12.0+ds-17.12.0+ds-27.12.0+ds-37.13.0+ds-17.13.0+ds-27.14.0+ds-1	None known
`calibre` Debian:13	All versions, plus listed versions 8.10.0+ds-18.10.0+ds-28.10.0+ds-38.11.0+ds+~0.10.5-18.11.1+ds+~0.10.5-1 Show 45 moreShow less 8.11.1+ds+~0.10.5-28.11.1+ds+~0.10.5-38.12.0+ds+~0.10.5-18.13.0+ds+~0.10.5-18.13.0+ds+~0.10.5-28.13.0+ds+~0.10.5-38.14.0+ds+~0.10.5-18.14.0+ds+~0.10.5-1~bpo13+18.15.0+ds+~0.10.5-18.15.0+ds+~0.10.5-1~bpo13+18.15.0+ds+~0.10.5-28.16.0+ds+~0.10.5-18.16.0+ds+~0.10.5-28.16.1+ds+~0.10.5-18.16.2+ds+~0.10.5-18.16.2+ds+~0.10.5-28.16.2+ds+~0.10.5-38.16.2+ds+~0.10.5-3~bpo13+18.5.0+ds-18.5.0+ds-1+deb13u18.5.0+ds-1+deb13u28.5.0+ds-1+deb13u38.6.0+ds-18.7.0+ds-18.8.0+ds-18.8.0+ds-28.8.0+ds-2+gcc158.8.0+ds-38.9.0+ds-18.9.0+ds-28.9.0+ds-38.9.0+ds-49.0.0+ds+~0.10.5-19.1.0+ds+~0.10.5-19.10.0+ds+~0.10.6-19.10.0+ds+~0.10.6-29.11.0+ds+~0.10.6-19.11.0+ds+~0.10.6-29.12.0+ds+~0.10.6-19.13.0+ds+~0.10.6-19.14.0+ds+~0.10.6-19.14.0+ds+~0.10.6-29.15.0+ds+~1.1.2-19.15.0+ds+~1.1.2-29.15.0+ds+~1.1.2-3	None known
`calibre` Debian:14	before 9.12.0+ds+~0.10.6-1, plus listed versions 8.10.0+ds-18.10.0+ds-28.10.0+ds-38.11.0+ds+~0.10.5-18.11.1+ds+~0.10.5-1 Show 45 moreShow less 8.11.1+ds+~0.10.5-28.11.1+ds+~0.10.5-38.12.0+ds+~0.10.5-18.13.0+ds+~0.10.5-18.13.0+ds+~0.10.5-28.13.0+ds+~0.10.5-38.14.0+ds+~0.10.5-18.14.0+ds+~0.10.5-1~bpo13+18.15.0+ds+~0.10.5-18.15.0+ds+~0.10.5-1~bpo13+18.15.0+ds+~0.10.5-28.16.0+ds+~0.10.5-18.16.0+ds+~0.10.5-28.16.1+ds+~0.10.5-18.16.2+ds+~0.10.5-18.16.2+ds+~0.10.5-28.16.2+ds+~0.10.5-38.16.2+ds+~0.10.5-3~bpo13+18.5.0+ds-18.6.0+ds-18.7.0+ds-18.8.0+ds-18.8.0+ds-28.8.0+ds-2+gcc158.8.0+ds-38.9.0+ds-18.9.0+ds-28.9.0+ds-38.9.0+ds-49.0.0+ds+~0.10.5-19.1.0+ds+~0.10.5-19.10.0+ds+~0.10.6-19.10.0+ds+~0.10.6-29.11.0+ds+~0.10.6-19.11.0+ds+~0.10.6-29.2.0+ds+~0.10.5-19.2.1+ds+~0.10.5-19.2.1+ds+~0.10.5-29.3.0+ds+~0.10.5-19.3.1+ds+~0.10.5-19.4.0+ds+~0.10.5-19.5.0+ds+~0.10.5-19.6.0+ds+~0.10.5-19.6.0+ds+~0.10.5-29.6.0+ds+~0.10.5-3	9.12.0+ds+~0.10.6-1
`calibre` Ubuntu:16.04:LTS	All versions, plus listed versions 2.33.0+dfsg-1build12.38.0+dfsg-12.45.0+dfsg-12.45.0+dfsg-1build12.48.0+dfsg-1 Show 4 moreShow less 2.48.0+dfsg-1build12.54.0+dfsg-12.55.0+dfsg-12.55.0+dfsg-1ubuntu0.2	None known
`calibre` Ubuntu:18.04:LTS	All versions, plus listed versions 3.7.0+dfsg-23.7.0+dfsg-2build13.12.0+dfsg-13.13.0+dfsg-13.14.0+dfsg-1 Show 10 moreShow less 3.15.0.1+dfsg-13.16.0+dfsg-13.16.0+dfsg-1build13.17.0+dfsg-13.17.0+dfsg-23.18.0+dfsg-1build13.19.0+dfsg-13.20.0+dfsg-13.21.0+dfsg-13.21.0+dfsg-1build1	None known
`calibre` Ubuntu:20.04:LTS	All versions, plus listed versions 3.46.0+dfsg-14.2.0+dfsg-24.3.0+dfsg-14.3.0+dfsg-24.4.0+dfsg-1 Show 14 moreShow less 4.5.0+dfsg-14.5.0+dfsg-24.5.0+dfsg-34.6.0+dfsg-14.7.0+dfsg-14.99.3+dfsg-24.99.4+dfsg-14.99.4+dfsg-1build14.99.4+dfsg+really4.10.0+py3-24.99.4+dfsg+really4.11.2-14.99.4+dfsg+really4.11.2-1build14.99.4+dfsg+really4.12.0-14.99.4+dfsg+really4.12.0-1build14.99.4+dfsg+really4.12.0-1ubuntu1	None known
`calibre` Ubuntu:22.04:LTS	All versions, plus listed versions 5.25.0+dfsg-25.33.2+dfsg-15.34.0+dfsg-15.35.0+dfsg-1ubuntu25.37.0+dfsg-15.37.0+dfsg-1build1	None known
`calibre` Ubuntu:24.04:LTS	All versions, plus listed versions 6.24.0+ds-16.29.0+ds-17.0.0+ds-17.1.0+ds-17.1.0+ds-2 Show 9 moreShow less 7.2.0+ds-17.2.0+ds-1build17.3.0+ds-17.4.0+ds-17.5.1+ds-17.5.1+ds-27.5.1+ds-37.6.0+ds-17.6.0+ds-1build1	None known
`calibre` Ubuntu:26.10	All versions, plus listed versions 9.2.1+ds+~0.10.5-2build19.9.0+ds+~0.10.6-19.11.0+ds+~0.10.6-19.11.0+ds+~0.10.6-29.13.0+ds+~0.10.6-19.14.0+ds+~0.10.6-2build1	None known
`calibre` Ubuntu:26.04:LTS	All versions, plus listed versions 8.8.0+ds-3build18.13.0+ds+~0.10.5-38.14.0+ds+~0.10.5-18.15.0+ds+~0.10.5-18.16.0+ds+~0.10.5-2 Show 4 moreShow less 8.16.2+ds+~0.10.5-18.16.2+ds+~0.10.5-28.16.2+ds+~0.10.5-39.2.1+ds+~0.10.5-2build1	None known

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-73248 is a high vulnerability (CVSS 8.5) in Kovidgoyal Calibre, published August 11, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.20%, the 9th percentile. Fixed in calibre 9.12.0+ds+~0.10.6-1.

References

This page doesn't list everything

Left out here: 158 versions. The JSON record has them.