CVE-2026-25636Public exploit

Arbitrary file corruption via EPUB path traversal

Published Feb 6, 2026 · Updated Feb 6, 2026

Path traversal in calibre 9.1.0 and earlier allows attackers to corrupt writable files when a user converts a malicious EPUB. The process_encryption method resolves unchecked CipherReference URI traversal segments and passes the escaped path to decrypt_font for XOR modification. GUI or ebook-convert conversion and an existing writable target are required; predictable target content can turn shell-startup-file corruption into code execution.

CVSS severity8.2
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Path traversal in calibre 9.1.0 and earlier allows attackers to corrupt writable files when a user converts a malicious EPUB. The process_encryption method resolves unchecked CipherReference URI traversal segments and passes the escaped path to decrypt_font for XOR modification. GUI or ebook-convert conversion and an existing writable target are required; predictable target content can turn shell-startup-file corruption into code execution.

The record

CVE
CVE-2026-25636
Published
Feb 6, 2026
Updated
Feb 6, 2026
Vendor
Kovid Goyal
Product
calibre
Classifications
CWE-94, CWE-22, CWE-73, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=< 9.2.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Kovid Goyal · calibreversion=< 9.2.0

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.2GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:H

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-94Improper Control of Generation of Code ('Code Injection')
CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-73External Control of File Name or Path
T1204.002Malicious File

Public exploit references

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo