# CVE-2026-27810: calibre: calibre is a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books

CVE-2026-27810 is fixed in calibre on 1 platform, first by DEBIAN-CVE-2026-27810, released February 27, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-27810
- Priority: Routine
- CVSS: 6.4 (medium)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 27, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | calibre Debian 12.15 (bookworm) | 6.13.0+repack-2+deb12u6 | [DEBIAN-CVE-2026-27810](https://patchblox.com/security/data/fix/linux/debian-cve-2026-27810.md) | Feb 27, 2026 |
| Linux | calibre Debian 13.5 (trixie) | 8.5.0+ds-1+deb13u2 | [DEBIAN-CVE-2026-27810](https://patchblox.com/security/data/fix/linux/debian-cve-2026-27810.md) | Feb 27, 2026 |
| Linux | calibre Debian 14 | 9.4.0+ds+~0.10.5-1 | [DEBIAN-CVE-2026-27810](https://patchblox.com/security/data/fix/linux/debian-cve-2026-27810.md) | Feb 27, 2026 |

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Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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