Raw vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:HSummary
CVE-2026-25635 is a high-severity Path Traversal (CWE-22) vulnerability in Calibre-Ebook Calibre. Its CVSS base score is 8.6 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 36th 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 SI-10 (Information Input Validation) — 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-2026-25635 is a path traversal vulnerability (CWE-22) in the CHM reader component of Calibre, an open-source e-book management application. Versions of Calibre prior to 9.2.0 are affected, enabling attackers to perform arbitrary file writes to any location where the affected user has write permissions.
The vulnerability can be exploited by a local attacker with no privileges required, though it demands user interaction such as opening a malicious CHM file in Calibre. Exploitation allows arbitrary file writes, which on Windows can escalate to code execution by placing a malicious payload in the Startup folder, triggering execution upon the user's next login. The CVSS v3.1 base score is 8.6 (AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H), indicating high confidentiality, integrity, and availability impacts with a changed scope.
Calibre addresses this issue in version 9.2.0. Mitigation details are provided in the GitHub security advisory (GHSA-32vh-whvh-9fxr), the fixing commit (9739232fcb029ac15dfe52ccd4fdb4a07ebb6ce9), and an independent analysis at 0x5t.raptx.org/posts/calibre-chm-rce. Users should update to 9.2.0 or later and avoid opening untrusted CHM files.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-5596
Vulnerability Data
calibre is an e-book manager. Prior to 9.2.0, Calibre's CHM reader contains a path traversal vulnerability that allows arbitrary file writes anywhere the user has write permissions. On Windows (haven't tested on other OS's), this can lead to Remote Code…
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Execution by writing a payload to the Startup folder, which executes on next login. 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
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V5.3.2
Mitigating Controls (NIST 800-53 r5) AI
Enforces the intended directory access authorizations that path traversal would otherwise bypass.
Input validation directly neutralizes special path elements before pathname construction occurs.
Least privilege reduces the impact of any unauthorized file access obtained via traversal.
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.
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.AA-05 defines and reviews access policies but does not address code-level pathname neutralization, so neither direction prevents CWE-22.
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.