{"id":"DEBIAN-CVE-2026-27824","details":"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.","modified":"2026-10-01T03:03:07.850558262Z","published":"2026-02-27T20:21:39.973Z","upstream":["CVE-2026-27824"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-27824"}],"affected":[{"package":{"name":"calibre","ecosystem":"Debian:12","purl":"pkg:deb/debian/calibre?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.13.0+repack-2+deb12u6"}]}],"versions":["6.13.0+repack-2","6.13.0+repack-2+deb12u1","6.13.0+repack-2+deb12u2","6.13.0+repack-2+deb12u3","6.13.0+repack-2+deb12u4","6.13.0+repack-2+deb12u5"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-27824.json"}},{"package":{"name":"calibre","ecosystem":"Debian:13","purl":"pkg:deb/debian/calibre?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.5.0+ds-1+deb13u2"}]}],"versions":["8.5.0+ds-1","8.5.0+ds-1+deb13u1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-27824.json"}},{"package":{"name":"calibre","ecosystem":"Debian:14","purl":"pkg:deb/debian/calibre?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"9.4.0+ds+~0.10.5-1"}]}],"versions":["8.10.0+ds-1","8.10.0+ds-2","8.10.0+ds-3","8.11.0+ds+~0.10.5-1","8.11.1+ds+~0.10.5-1","8.11.1+ds+~0.10.5-2","8.11.1+ds+~0.10.5-3","8.12.0+ds+~0.10.5-1","8.13.0+ds+~0.10.5-1","8.13.0+ds+~0.10.5-2","8.13.0+ds+~0.10.5-3","8.14.0+ds+~0.10.5-1","8.14.0+ds+~0.10.5-1~bpo13+1","8.15.0+ds+~0.10.5-1","8.15.0+ds+~0.10.5-1~bpo13+1","8.15.0+ds+~0.10.5-2","8.16.0+ds+~0.10.5-1","8.16.0+ds+~0.10.5-2","8.16.1+ds+~0.10.5-1","8.16.2+ds+~0.10.5-1","8.16.2+ds+~0.10.5-2","8.16.2+ds+~0.10.5-3","8.16.2+ds+~0.10.5-3~bpo13+1","8.5.0+ds-1","8.6.0+ds-1","8.7.0+ds-1","8.8.0+ds-1","8.8.0+ds-2","8.8.0+ds-2+gcc15","8.8.0+ds-3","8.9.0+ds-1","8.9.0+ds-2","8.9.0+ds-3","8.9.0+ds-4","9.0.0+ds+~0.10.5-1","9.1.0+ds+~0.10.5-1","9.2.0+ds+~0.10.5-1","9.2.1+ds+~0.10.5-1","9.2.1+ds+~0.10.5-2","9.3.0+ds+~0.10.5-1","9.3.1+ds+~0.10.5-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-27824.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"}]}