CVE-2020-24553: Cross-Site Scripting Vulnerability in net/http/cgi and net/http/fcgi Packages

Sponsored Habilume Habit tracker with a companion that grows with you Complete habits, earn Lume Points, and watch your Lume grow as you stay consistent. App Store Google Play

Background

The net/http/cgi and net/http/fcgi packages in the Go ecosystem provide functionality for handling Common Gateway Interface (CGI) and FastCGI requests in Go applications. These packages are commonly used to build web servers and handle HTTP requests. However, a vulnerability has been identified in these packages that can lead to a Cross-Site Scripting (XSS) attack if an attacker can control any part of the response content.

Vulnerability Detail

The vulnerability arises when a Handler does not explicitly set the Content-Type header in the response. In such cases, the net/http/cgi and net/http/fcgi packages default to "text/html" as the Content-Type. This default behavior can be exploited by an attacker to inject malicious scripts into the response, leading to a Cross-Site Scripting vulnerability. If successful, the attacker can execute arbitrary JavaScript code in the context of the victim's browser, potentially compromising sensitive user information or performing unauthorized actions.

go get stdlib@vgo1.25.5

Workaround

As a workaround, developers can manually set the Content-Type header to a safe value, such as "text/plain", for responses that do not contain HTML content. This prevents the browser from interpreting the response as HTML and mitigates the risk of XSS attacks. Here is an example of how to set the Content-Type header in a Go HTTP handler:

func handler(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "text/plain")
    // Rest of the handler code
}

Conclusion

The net/http/cgi and net/http/fcgi packages in the Go ecosystem are vulnerable to a Cross-Site Scripting (XSS) attack when the Content-Type header is not explicitly set in the response. This can allow an attacker to inject and execute arbitrary JavaScript code in the victim's browser. To mitigate this vulnerability, developers should ensure that the Content-Type header is set appropriately for each response. It is recommended to review the code and apply the necessary fixes to prevent potential exploitation. For further support on vulnerability remediation, you can contact DevNack.com.

See every vulnerability recorded for stdlib →

FAQ