CVE-2009-3287: Macournoyer Thin

High severity, CVSS 7.5. EPSS: 1.4% chance of exploitation in the next 30 days.

lib/thin/connection.rb in Thin web server before 1.2.4 relies on the X-Forwarded-For header to determine the IP address of the client, which allows remote attackers to spoof the IP address and hide activities via a modified X-Forwarded-For header.

Affected products

• Macournoyer Thin: up to and including 1.2.2; version 0.4.0 only; version 0.4.1 only; version 0.5.0 only; version 0.5.1 only; version 0.5.2 only; …

Published 2009-09-22. Last modified 2026-06-16.