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 Servers 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.
Weakness
The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Calibre | Calibre-ebook | * | 9.4.0 (excluding) |
| Calibre | Ubuntu | upstream | * |
Potential Mitigations
Common protection mechanisms include:
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
Consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator. [REF-45]
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/16.html
- https://cwe.mitre.org/data/definitions/49.html
- https://cwe.mitre.org/data/definitions/560.html
- https://cwe.mitre.org/data/definitions/565.html
- https://cwe.mitre.org/data/definitions/600.html
- https://cwe.mitre.org/data/definitions/652.html
- https://cwe.mitre.org/data/definitions/653.html