Read the docs
TI-2026-51385 Aliases CVE-2026-73248

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

Priority HIGH 72CWE-94Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-94.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00197 9th percentileScored 2026-11-07
Fix Fixed calibre (kovidgoyal): 9.12.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
kovidgoyalcalibrebefore 9.12.09.12.0Patch availableCNA
  • calibre Vendorkovidgoyal Affected before 9.12.0 Fixed in 9.12.0 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:calibre-ebook:calibre:*:*:*:*:*:*:*:*——Calibre
  • cpe:2.3:a:calibre-ebook:calibre:*:*:*:*:*:*:*:* Versions — — ·Calibre

Remediation

  • Fix · CNA calibre (kovidgoyal) Fixed in 9.12.0

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-73248

References

Other 3

  • TI-2026-26023 Kitty has a Heap Buffer Over-Read/Write via Integer Overflow in compose_rectangles Bounds Check CVSS 3.1CRITICAL 9.9
  • TI-2026-51129 Kitty: Command injection into the child shell via chained @kitty-echo + @kitty-ssh DCS escape sequences CVSS 4.0HIGH 7.3
  • TI-2026-26014 Kitty has a Heap Buffer Overflow in its Graphics Protocol Handler CVSS 3.1HIGH 8.8
  • TI-2026-51386 Missing authorization in kovidgoyal calibre CVSS 3.1HIGH 7.5
  • TI-2026-38585 calibre: Arbitrary Code Execution in Template Formatter via Book Metadata CVSS 4.0HIGH 8.5
  • TI-2026-25627 calibre has a path traversal vulnerability CVSS 4.0HIGH 8.2
See all 29 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences