Calibre
CVE-2026-25636
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessCraft malicious EPUB with path traversal in encryption.xml
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DeliveryUser opens EPUB in Calibre conversion
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ExploitCipherReference URI resolves to arbitrary file path
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ExecutionCalibre opens file in read-write mode
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ImpactAttacker corrupts arbitrary files
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V5 - File Handling Path canonicalization, traversal prevention
MITRE ATT&CK
2 techniques across 2 tactics: Discovery, Collection The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Calibre versions 9.1.0 and earlier with EPUB conversion feature enabled. User must initiate EPUB file conversion. Attacker crafts malicious EPUB with CipherReference URI in META-INF/encryption.xml pointing outside extraction directory to target writable files accessible by Calibre process. |
| Impact | CVSS 8.2 (HIGH). Attack vector: Local. Complexity: Low. Privileges required: None. User interaction: Required. Public exploit/POC available. |
| Exploit ScenarioDerived | An attacker could exploit this vulnerability to compromise the affected system. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Calibre 9.1.0 and earlier contains a path traversal vulnerability in EPUB conversion that allows malicious EPUB files to corrupt or modify arbitrary files writable by the Calibre process. The vulnerability exploits improper handling of CipherReference URIs in encryption metadata, enabling attackers to write outside the intended extraction directory. Public exploit code exists for this high-severity issue, which is patched in version 9.2.0.
Earlier versions of this analysis (1)
calibre is an e-book manager. In 9.1.0 and earlier, a path traversal vulnerability in Calibre's EPUB conversion allows a malicious EPUB file to corrupt arbitrary existing files writable by the Calibre process. [CVSS 8.2 HIGH]
RemediationAI
A vendor patch is available — apply it immediately. Fixed in version 9.2.0.. Validate and sanitize file path inputs. Use allowlists.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-22 (Path Traversal). Affects Calibre. calibre is an e-book manager. In 9.1.0 and earlier, a path traversal vulnerability in Calibre's EPUB conversion allows a malicious EPUB file to corrupt arbitrary existing files writable by the Calibre process. During conversion, Calibre resolves CipherReference URI from META-INF/encryption.xml to an absolute filesystem path and opens it in read-write mode, even when it points outside the conversion extraction directory. This vulnerability is fixed in 9.2.0.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:H
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
Lifecycle Timeline
3DescriptionGitHub Advisory
calibre is an e-book manager. In 9.1.0 and earlier, a path traversal vulnerability in Calibre's EPUB conversion allows a malicious EPUB file to corrupt arbitrary existing files writable by the Calibre process. During conversion, Calibre resolves CipherReference URI from META-INF/encryption.xml to an absolute filesystem path and opens it in read-write mode, even when it points outside the conversion extraction directory. This vulnerability is fixed in 9.2.0.
Executive ViewAI
Calibre e-book management software contains a critical path traversal vulnerability that allows attackers to corrupt arbitrary files through malicious EPUB files. Organizations using Calibre are at immediate risk of data loss and system compromise if users process untrusted EPUB files, with public exploits already available.
Apply vendor patch.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Path traversal exploits occur when applications use user-controlled input to construct file system paths without proper validation.
Affected Products (CPE)GitHub Advisory
Remote code execution in Calibre 9.2.1 and earlier allows authenticated users to write arbitrary files via a path traver
Calibre versions 9.2.1 and below allow authenticated users to write arbitrary files with any extension to any writable l
Remote code execution in Calibre prior to version 9.2.0 through a path traversal flaw in the CHM reader allows local att
calibre is an e-book manager. [CVSS 7.8 HIGH]
gui2/viewer/bookmarkmanager.py in Calibre 3.18 calls cPickle.load on imported bookmark data, which allows remote attacke
Path traversal in Calibre <= 7.14.0 allow unauthenticated attackers to achieve arbitrary file read. Rated high severity
link_to_local_path in ebooks/conversion/plugins/html_input.py in calibre before 6.19.0 can, by default, add resources ou
calibre before 5.32.0 contains a regular expression that is vulnerable to ReDoS (Regular Expression Denial of Service) i
Unsanitized user-input in Calibre <= 7.15.0 allow users with permissions to perform full-text searches to achieve SQL in
HTTP response header injection in Calibre Content Server prior to version 9.4.0 permits authenticated users to inject ar
Unsanitized user-input in Calibre <= 7.15.0 allow attackers to perform reflected cross-site scripting. Rated medium seve
The E-book viewer in calibre before 2.75 allows remote attackers to read arbitrary files via a crafted epub file with Ja
Exploit-DB