kovidgoyal calibre up to 9.3.x HTTP Response Header /get/ content_disposition response splitting

Summaryinfo

A vulnerability marked as critical has been reported in kovidgoyal calibre up to 9.3.x. This vulnerability affects unknown code of the file /get/ of the component HTTP Response Header Handler. Performing a manipulation of the argument content_disposition results in response splitting. This vulnerability is cataloged as CVE-2026-27810. It is possible to initiate the attack remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in kovidgoyal calibre up to 9.3.x. This affects an unknown code of the file /get/ of the component HTTP Response Header Handler. The manipulation of the argument content_disposition with an unknown input leads to a response splitting vulnerability. CWE is classifying the issue as CWE-113. The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

calibre is a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books. Prior to version 9.4.0, an HTTP Response Header Injection vulnerability in the calibre Content Server allows any authenticated user to inject arbitrary HTTP headers into server responses via an unsanitized `content_disposition` query parameter in the `/get/` and `/data-files/get/` endpoints. All users running the calibre Content Server with authentication enabled are affected. The vulnerability is exploitable by any authenticated user and can also be triggered by tricking an authenticated victim into clicking a crafted link. Version 9.4.0 contains a fix for the issue.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-27810 since 02/24/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 300512 (Linux Distros Unpatched Vulnerability : CVE-2026-27810), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 9.4.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (300512) and EUVD (EUVD-2026-9056). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• kovidgoyal

Name

• calibre

Version

• 9.0
• 9.1
• 9.2
• 9.3

Website

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

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Discussion