Summaryinfo

A vulnerability labeled as critical has been found in kovidgoyal calibre up to 9.5.x. This affects an unknown part of the component background-image Endpoint. The manipulation results in server-side request forgery. This vulnerability is identified as CVE-2026-33205. The attack can be executed remotely. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical has been found in kovidgoyal calibre up to 9.5.x. Affected is an unknown part of the component background-image Endpoint. The manipulation with an unknown input leads to a server-side request forgery vulnerability. CWE is classifying the issue as CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

calibre is a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books. Prior to version 9.6.0, a Server-Side Request Forgery vulnerability in the background-image endpoint of calibre e-book reader's web view allows an attacker to perform blind GET requests to arbitrary URLs and exfiltrate information out from the ebook sandbox. Version 9.6.0 patches the issue.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-33205 since 03/18/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 304173 (Linux Distros Unpatched Vulnerability : CVE-2026-33205), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 9.6.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (304173). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

• kovidgoyal

Name

• calibre

Version

• 9.0
• 9.1
• 9.2
• 9.3
• 9.4
• 9.5

Website

• Product: https://github.com/kovidgoyal/calibre/

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