CVE catalog
CVE-2026-27824
calibre is a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books. Prior to version 9.4.0, the calibre Content Server's brute-force protection mechanism uses a ban ke
- Severity
- Medium · CVSS 5.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.17% · Oct 27, 2026
calibre is a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books. Prior to version 9.4.0, the calibre Content Server's brute-force protection mechanism uses a ban key derived from both `remote_addr` and the `X-Forwarded-For` header. Since the `X-Forwarded-For` header is read directly from the HTTP request without any validation or trusted-proxy configuration, an attacker can bypass IP-based bans by simply changing or adding this header, rendering the brute-force protection completely ineffective. This is particularly dangerous for calibre servers exposed to the internet, where brute-force protection is the primary defense against credential stuffing and password guessing attacks. Version 9.4.0 contains a fix for the issue.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | calibre | sid | 9.17.0+ds+~1.1.2-1 | fixed |
| Debian | calibre | forky | 9.17.0+ds+~1.1.2-1 | fixed |
| Debian | calibre | trixie | 8.5.0+ds-1+deb13u3 | fixed |
| Debian | calibre | bookworm | 6.13.0+repack-2+deb12u9 | fixed |
| Debian | calibre | bookworm-security | 6.13.0+repack-2+deb12u10 | fixed |
| Cpe | calibre | Not reported | Not reported | vulnerable |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | calibre | source | sid | 9.4.0+ds+~0.10.5-1 | not yet assigned | Not reported | Not reported |
| Debian | calibre | source | forky | 9.4.0+ds+~0.10.5-1 | not yet assigned | Not reported | Not reported |
| Debian | calibre | source | trixie | 8.5.0+ds-1+deb13u2 | not yet assigned | Not reported | Not reported |
| Debian | calibre | source | bookworm | 6.13.0+repack-2+deb12u6 | not yet assigned | Not reported | Not reported |
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [calibre]Fixed
Details (4)
6.13.0+repack-2+deb12u9· all · bookwormFixed · Fixed:
6.13.0+repack-2+deb12u6nvd · calibre · debian · bookworm; nvd · calibre · debian · 12
6.13.0+repack-2+deb12u9· all · bookwormFixed · Fixed:
6.13.0+repack-2+deb12u6nvd · calibre · debian · bookworm; nvd · calibre · debian · 12
6.13.0+repack-2+deb12u10· all · bookworm-securityFixed · Fixed:
6.13.0+repack-2+deb12u6nvd · calibre · debian · bookworm; nvd · calibre · debian · 12
6.13.0+repack-2+deb12u10· all · bookworm-securityFixed · Fixed:
6.13.0+repack-2+deb12u6nvd · calibre · debian · bookworm; nvd · calibre · debian · 12
- [calibre-bin]Fixed
Source package: [calibre]
Details (4)
6.13.0+repack-2+deb12u9· amd64 · bookwormFixed · Fixed:
6.13.0+repack-2+deb12u6nvd · calibre · debian · bookworm; nvd · calibre · debian · 12
6.13.0+repack-2+deb12u9· arm64 · bookwormFixed · Fixed:
6.13.0+repack-2+deb12u6nvd · calibre · debian · bookworm; nvd · calibre · debian · 12
6.13.0+repack-2+deb12u10· amd64 · bookworm-securityFixed · Fixed:
6.13.0+repack-2+deb12u6nvd · calibre · debian · bookworm; nvd · calibre · debian · 12
6.13.0+repack-2+deb12u10· arm64 · bookworm-securityFixed · Fixed:
6.13.0+repack-2+deb12u6nvd · calibre · debian · bookworm; nvd · calibre · debian · 12
[Debian 13 (Trixie)]
- [calibre]Fixed
Details (4)
8.5.0+ds-1+deb13u3· all · trixieFixed · Fixed:
8.5.0+ds-1+deb13u2nvd · calibre · debian · 13
8.5.0+ds-1+deb13u3· all · trixieFixed · Fixed:
8.5.0+ds-1+deb13u2nvd · calibre · debian · 13
8.16.2+ds+~0.10.5-3~bpo13+1· all · trixie-backportsFixed · Fixed:
8.5.0+ds-1+deb13u2nvd · calibre · debian · 13
8.16.2+ds+~0.10.5-3~bpo13+1· all · trixie-backportsFixed · Fixed:
8.5.0+ds-1+deb13u2nvd · calibre · debian · 13
- [calibre-bin]Fixed
Source package: [calibre]
Details (4)
8.5.0+ds-1+deb13u3· amd64 · trixieFixed · Fixed:
8.5.0+ds-1+deb13u2nvd · calibre · debian · 13
8.5.0+ds-1+deb13u3· arm64 · trixieFixed · Fixed:
8.5.0+ds-1+deb13u2nvd · calibre · debian · 13
8.16.2+ds+~0.10.5-3~bpo13+1· amd64 · trixie-backportsFixed · Fixed:
8.5.0+ds-1+deb13u2nvd · calibre · debian · 13
8.16.2+ds+~0.10.5-3~bpo13+1· arm64 · trixie-backportsFixed · Fixed:
8.5.0+ds-1+deb13u2nvd · calibre · debian · 13
Observed:
References
- [https://ftp.suse.com/pub/projects/security/csaf/opensuse-su-2026_10587-1.json]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-27824]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-27824]
- [https://security-tracker.debian.org/tracker/CVE-2026-27824]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27824.json]
[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]