CVE-2026-27810

low-risk
Published 2026-02-27

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.

Do I need to act?

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0.05% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
6
CVSS 6.4/10 Medium
NETWORK / LOW complexity

Affected Products (1)

Affected Vendors

Calibre-Ebook

References (1)

Exploit https://github.com/kovidgoyal/calibre/security/advisories/GHSA-5fpj-fxw7-8grw
29
/ 100
low-risk
Severity 24/34 · High
Exploitability 0/34 · Minimal
Exposure 5/34 · Minimal