What is CVE-2026-27824?

CVE-2026-27824 is a medium-severity vulnerability in Kovidgoyal Calibre, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 5.3/10. Published 2026-02-27.

How severe is CVE-2026-27824?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Kovidgoyal Calibre

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 key derived from both `remote_addr` and t…

EPSS: 0.000 (10.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

Affected products

Kovidgoyal Calibre — versions < 9.4.0

Weakness classification (CWE)

References

https://github.com/kovidgoyal/calibre/security/advisories/GHSA-vhxc-r7v8-2xrw (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-27824?: CVE-2026-27824 is a medium-severity vulnerability in Kovidgoyal Calibre, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 5.3/10. Published 2026-02-27.
How severe is CVE-2026-27824?: Medium severity. CVSS v3 base score is 5.3 out of 10.