Path Traversal in Calibre-Ebook Calibre

CVE-2026-30853

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 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.

Vulnerability class: Path Traversal (Directory Traversal)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.0 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:L.

EPSS exploit prediction

EPSS: 0.002 (7.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 7.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-30853: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-30853?
CVE-2026-30853 is a medium-severity vulnerability in Calibre-Ebook Calibre, classified under Path Traversal. CVSS score: 5.0/10. Published 2026-03-13.
How severe is CVE-2026-30853?
Medium severity. CVSS v3 base score is 5.0 out of 10.