Path traversal in Calibre - CVE-2026-25635
Published: June 29, 2026
Vulnerability identifier: #VU135809
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-25635
CWE-ID: CWE-22
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Calibre
Affected software:
Calibre
Calibre
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to path traversal in src/calibre/ebooks/chm/reader.py when processing a crafted CHM file during conversion. A remote attacker can trick the victim into converting a malicious CHM file to execute arbitrary code.
On Windows, arbitrary file write outside the extraction directory can be leveraged by placing a payload in the Startup folder, which executes on the next login. User interaction is required to convert the crafted CHM file via the GUI or the ebook-convert CLI.
How to mitigate CVE-2026-25635
Install security update from vendor's website.