Raw vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:LSummary
CVE-2026-30853 is a medium-severity Path Traversal (CWE-22) vulnerability in Calibre-Ebook Calibre. Its CVSS base score is 5.0 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 8th 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.
Calibre, a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books, suffers from a path traversal vulnerability (CWE-22) in its RocketBook (.rb) input plugin at src/calibre/ebooks/rb/reader.py. This issue affects versions prior to 9.5.0 and enables an attacker to write arbitrary files to any path writable by the calibre process upon a user opening or converting a crafted .rb file.
The attack requires local access (AV:L) with no privileges (PR:N) but relies on user interaction (UI:R), such as deliberately opening or converting a malicious .rb file. Successful exploitation allows limited integrity (I:L) and availability (A:L) impacts within a scoped attack surface (S:C), earning a CVSS 3.1 base score of 5.0.
The vulnerability is remediated in calibre 9.5.0. Additional details are available in the GitHub security advisory at https://github.com/kovidgoyal/calibre/security/advisories/GHSA-7mp7-rfrg-542x. This flaw belongs to the same bug class previously fixed in CVE-2026-26065 for PDB readers, though that patch was not extended to the RB reader.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-12069
Vulnerability Data
calibre is a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books. Prior to 9.5.0, a path traversal vulnerability in the RocketBook (.rb) input plugin (src/calibre/ebooks/rb/reader.py) allows an attacker to write arbitrary files to any path writable by the…
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calibre process when a user opens or converts a crafted .rb file. This is the same bug class fixed in CVE-2026-26065 for the PDB readers, but the fix was never applied to the RB reader. This vulnerability is fixed in 9.5.0.
- 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.