CVE-2026-53511Public exploit

Arbitrary code execution via embedded Python template

Published Jul 7, 2026 · Updated Jul 7, 2026

Code injection in Kovid Goyal calibre before 9.10.0 allows attackers to execute arbitrary Python code via malicious book metadata. Metadata readers store unvalidated calibre:user_metadata definitions, and the formatter passes an embedded python template through safe_format to exec(). A user must add, edit, or otherwise read the crafted EPUB, OPF, or PDF; the payload then runs with that user's calibre process permissions.

CVSS severity8.5
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in Kovid Goyal calibre before 9.10.0 allows attackers to execute arbitrary Python code via malicious book metadata. Metadata readers store unvalidated calibre:user_metadata definitions, and the formatter passes an embedded python template through safe_format to exec(). A user must add, edit, or otherwise read the crafted EPUB, OPF, or PDF; the payload then runs with that user's calibre process permissions.

The record

CVE
CVE-2026-53511
Published
Jul 7, 2026
Updated
Jul 7, 2026
Vendor
Kovid Goyal
Product
calibre
Classifications
CWE-95, CWE-94, T1059.006, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 9.10.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Kovid Goyal · calibreversion=< 9.10.0

Published CVSS scores

8.5GitHubCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-95Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
CWE-94Improper Control of Generation of Code ('Code Injection')
T1059.006Command and Scripting Interpreter: Python
T1204.002User Execution: Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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