Raw vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:HSummary
CVE-2026-25636 is a high-severity Path Traversal (CWE-22) vulnerability in Calibre-Ebook Calibre. Its CVSS base score is 8.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 11th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and SA-11 (Developer Testing and Evaluation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-25636 is a path traversal vulnerability in Calibre, an e-book manager, affecting versions 9.1.0 and earlier. The flaw occurs during EPUB conversion, where Calibre resolves CipherReference URIs from META-INF/encryption.xml to absolute filesystem paths and opens them in read-write mode, even if the paths point outside the conversion extraction directory. This enables a malicious EPUB file to corrupt arbitrary existing files writable by the Calibre process. The issue is associated with CWEs-22, CWE-73, and CWE-94, and carries a CVSS v3.1 base score of 8.2 (AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:H).
An attacker with local access can exploit this vulnerability by providing a malicious EPUB file and tricking a user into converting it with Calibre, requiring no privileges or special conditions beyond user interaction. Upon conversion, the attacker can achieve high-impact integrity and availability disruption by corrupting files accessible to the Calibre process, with the attack scope changing to the file system. Confidentiality is not affected.
The vulnerability is addressed in Calibre 9.2.0. Mitigation details are outlined in the GitHub security advisory at https://github.com/kovidgoyal/calibre/security/advisories/GHSA-8r26-m7j5-hm29, with the fixing commit available at https://github.com/kovidgoyal/calibre/commit/9484ea82c6ab226c18e6ca5aa000fa16de598726. Further technical analysis appears at https://0x5t.raptx.org/posts/calibre-epub-rce.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-5597
Vulnerability Data
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…
more
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
—
V5.3.2V1.3.1
Mitigating Controls (NIST 800-53 r5) AI
Enforces the intended directory access authorizations that path traversal would otherwise bypass.
Developer testing and evaluation finds code paths that accept and execute externally influenced strings.
Input validation directly neutralizes special path elements before pathname construction occurs.
Least privilege reduces the impact of any unauthorized file access obtained via traversal.
Requiring documented secure development standards and tools enforces use of safe code-generation APIs and escaping.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices include input validation and path sanitization that eliminate this weakness.
Least-privilege file authorization directly limits damage from externally controlled paths.
Patching/maintenance can remediate known path-traversal flaws in deployed software (partial prevention of exploitability) but does nothing to stop the coding defect from being introduced in the first place.
PR.DS-10 protects runtime data confidentiality/integrity but has no bearing on neutralizing externally influenced input during code generation, so neither direction shows any preventive effect.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development catches path traversal via static/dynamic analysis.
Secure SDLC mandates input validation and path sanitization that directly prevent path traversal.
Application security requirements include rules for safe file handling and canonicalization.
Secure architecture principles require least-privilege file access and directory isolation.
Secure coding standards explicitly forbid unsafe path construction and mandate safe APIs.
Information access restriction limits which files an application may read or write.