CVE-2022-39348 in Twisted
Summary
by MITRE • 10/27/2022
Twisted is an event-based framework for internet applications. Started with version 0.9.4, when the host header does not match a configured host `twisted.web.vhost.NameVirtualHost` will return a `NoResource` resource which renders the Host header unescaped into the 404 response allowing HTML and script injection. In practice this should be very difficult to exploit as being able to modify the Host header of a normal HTTP request implies that one is already in a privileged position. This issue was fixed in version 22.10.0rc1. There are no known workarounds.
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Analysis
by VulDB Data Team • 04/28/2025
The vulnerability described in CVE-2022-39348 affects the Twisted web framework, an event-based internet application framework written in python. This issue specifically impacts versions 0.9.4 and later where the NameVirtualHost implementation fails to properly sanitize the Host header when it does not match a configured host. The flaw exists within the twisted.web.vhost.NameVirtualHost class which handles virtual hosting for web applications. When a request is made with a Host header that does not correspond to any configured virtual host, the framework returns a NoResource response that directly incorporates the unescaped Host header value into the HTML response body, creating a potential cross-site scripting vulnerability.
The technical nature of this vulnerability stems from improper input validation and output encoding within the web framework's virtual hosting mechanism. When the Host header value is not recognized as a valid configured host, the system returns a 404 error page that includes the raw Host header content without proper HTML escaping or sanitization. This creates a classic reflected cross-site scripting scenario where malicious input in the Host header can be executed as JavaScript within the victim's browser context. The vulnerability is classified under CWE-79 as a Cross-Site Scripting flaw, specifically involving the improper neutralization of input during web page generation. The ATT&CK framework categorizes this under T1203 as Exploitation for Client Execution, as the vulnerability enables remote code execution through browser-based attacks.
The operational impact of this vulnerability is significant despite its exploitation difficulty. While the attack requires control over the Host header, which typically indicates an already compromised network position, the potential for persistent malicious activity exists. An attacker who can manipulate HTTP requests may inject malicious scripts that could redirect users to phishing sites, steal session cookies, or perform other malicious actions. The vulnerability affects all applications built on Twisted web framework versions 0.9.4 through 22.10.0rc1, making it a widespread concern for organizations using this framework for web services. The fix implemented in version 22.10.0rc1 properly sanitizes the Host header value before incorporating it into response content, ensuring that any potentially malicious input is neutralized before rendering.
Organizations should prioritize upgrading to Twisted version 22.10.0rc1 or later to remediate this vulnerability. Since no known workarounds exist, the upgrade represents the primary defense mechanism. System administrators should also implement network monitoring to detect unusual Host header values that might indicate attempted exploitation. The vulnerability demonstrates the importance of proper input sanitization in web frameworks and highlights the need for comprehensive security testing of all user-controllable inputs in HTTP headers. Security teams should conduct vulnerability assessments to identify all applications using affected Twisted versions and ensure proper patch management procedures are in place to prevent similar issues in the future.