कैलिबर में पाथ ट्रैवर्सल से मनमाना फ़ाइल करप्शन और कोड एग्जीक्यूशन हो सकता है

An attacker could exploit this vulnerability by crafting a malicious EPUB file. When Calibre attempts to convert this file, the vulnerability allows the attacker to specify an arbitrary file path outside of the intended conversion directory. Calibre then opens this file in read-write mode, enabling the attacker to overwrite or delete existing files. The potential impact ranges from data corruption within the Calibre library to broader system compromise if Calibre runs with elevated privileges. This is particularly concerning for users who manage sensitive e-books or use Calibre on shared systems.

Users who manage e-books with Calibre, particularly those who download e-books from untrusted sources or use Calibre on shared systems, are at risk. Individuals using older versions of Calibre (≤ 9.2.0) are especially vulnerable. Users who rely on Calibre for managing sensitive documents should prioritize upgrading.

• windows / supply-chain: Monitor Calibre's process for unusual file access patterns using Process Monitor. Check registry keys related to Calibre for unexpected modifications.

Get-Process calibre | Select-Object Path

• linux / server: Monitor Calibre's process for file access using lsof. Examine system logs for errors related to file access during EPUB conversion.

lsof -p $(pidof calibre)

• generic web: Examine Calibre's access logs for requests containing suspicious file paths or URI schemes in the CipherReference URI. • database (mysql, redis, mongodb, postgresql): N/A - this vulnerability does not directly impact databases. • wordpress / composer / npm: N/A - this vulnerability does not directly impact these components.

1. 2026-02-06Disclosure

   disclosure

1. आरक्षित2026-02-04
2. प्रकाशित2026-02-06
3. संशोधित2026-02-11
4. EPSS अद्यतन2026-03-23

The primary mitigation for CVE-2026-25636 is to upgrade Calibre to version 9.2.0 or later, which contains the fix. If upgrading is not immediately feasible, consider restricting the types of EPUB files accepted from untrusted sources. Implement a strict file extension whitelist to prevent the processing of potentially malicious files. Monitor Calibre's file system access logs for unusual activity, particularly writes to unexpected locations. After upgrading, confirm the fix by attempting to convert a test EPUB file with a deliberately malformed CipherReference URI; the conversion should fail with an appropriate error message.