ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2026-27824

calibre is a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books.

Published Feb 27, 2026 · catalog updated Jun 17, 2026 · calibre is a cross-platform

Check if you run it

No confirmed exploitation is on record for CVE-2026-27824. EPSS is 0.19%. Act only if a listed version of calibre is a cross-platform is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (calibre is a cross-platform).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.19%
Remediation
Advisory link
Affected products
cpe calibre-ebook/calibre

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 and the header. Since the 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe calibre-ebook/calibreversion unspecified

How to fix CVE-2026-27824

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-27824. EPSS is 0.19%. Act only if a listed version of calibre is a cross-platform is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-307: Improper Restriction of Excessive Authentication Attempts; CWE-346. EPSS 0.19%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 27, 2026 · NIST NVD

    Detected

    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 and the header. Since the header is read directly from the HTTP request without any validation or trusted-proxy configuration, an attacker can bypass IP-based bans by simply changi

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 and the header. Since the header is read directly from the HTTP request without any validation or trusted-proxy configuration, an attacker can bypass IP-based bans by simply changi

Sources

  • CVE.orgVulnerability recordCVE-2026-27824

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-27824

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-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 and the header. Since the `X

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.