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TI-2026-20799 Aliases CVE-2026-25731

Calibre Affected by Arbitrary Code Execution via Server-Side Template Injection in Calibre HTML Export

Priority HIGH 69CWE-1336Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-1336.

Summary

calibre is an e-book manager. Prior to 9.2.0, a Server-Side Template Injection (SSTI) vulnerability in Calibre's Templite templating engine allows arbitrary code execution when a user converts an ebook using a malicious custom template file via the --template-html or --template-html-index command-line options. This vulnerability is fixed in 9.2.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00276 20th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed calibre (kovidgoyal): 9.2.0

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 9.2.09.2.0Patch availableCNA
  • calibre Vendorkovidgoyal Affected before 9.2.0 Fixed in 9.2.0 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:calibre-ebook:calibre:*:*:*:*:*:*:*:*before 9.2.0VulnerableCalibre
  • cpe:2.3:a:calibre-ebook:calibre:*:*:*:*:*:*:*:* Versions before 9.2.0 Vulnerable ·Calibre

Remediation

  • Fix · CNA calibre (kovidgoyal) Fixed in 9.2.0

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-2026-25731

References

Exploit 1

Patch 1

  • 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-2026-51385 calibre: Bypass of Python template restrictions via nested `template()` leading to RCE CVSS 4.0HIGH 8.5
  • TI-2026-38585 calibre: Arbitrary Code Execution in Template Formatter via Book Metadata CVSS 4.0HIGH 8.5
See all 29 →

Sources

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