What is CVE-2026-27810?

CVE-2026-27810 is a medium-severity vulnerability in Kovidgoyal Calibre, classified under HTTP Response Splitting. CVSS score: 6.4/10. Published 2026-02-27.

How severe is CVE-2026-27810?

Medium severity. CVSS v3 base score is 6.4 out of 10.

Vulnerability in Kovidgoyal Calibre

CVE-2026-27810

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 inj…

EPSS: 0.001 (21.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N.

Affected products

Kovidgoyal Calibre — versions < 9.4.0

Weakness classification (CWE)

CWE-113 — HTTP Response Splitting

References

https://github.com/kovidgoyal/calibre/security/advisories/GHSA-5fpj-fxw7-8grw (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-27810?: CVE-2026-27810 is a medium-severity vulnerability in Kovidgoyal Calibre, classified under HTTP Response Splitting. CVSS score: 6.4/10. Published 2026-02-27.
How severe is CVE-2026-27810?: Medium severity. CVSS v3 base score is 6.4 out of 10.