CVE-2025-30223: Beego Web Framework XSS Vulnerability

CVE-2025-30223 Overview

CVE-2025-30223 is a Cross-Site Scripting (XSS) vulnerability in Beego, an open-source web framework for the Go programming language. The vulnerability exists in Beego's RenderForm() function due to improper HTML escaping of user-controlled data. This flaw allows attackers to inject malicious JavaScript code that executes in victims' browsers, potentially leading to session hijacking, credential theft, or account takeover.

The vulnerability affects any application using Beego's RenderForm() function with user-provided data. Since RenderForm() is a high-level function that generates entire form markup, many developers would assume it automatically escapes attributes—as most modern frameworks do. This assumption creates a dangerous attack surface when processing untrusted input.

Critical Impact

Attackers can inject malicious JavaScript through unescaped form attributes, enabling session hijacking, credential theft, and full account takeover in affected Beego applications.

Affected Products

• Beego versions prior to 2.3.6
• Applications using the RenderForm() function with user-controlled data
• Go web applications built on the Beego framework

Discovery Timeline

• 2025-03-31 - CVE-2025-30223 published to NVD
• 2025-08-01 - Last updated in NVD database

Technical Details for CVE-2025-30223

Vulnerability Analysis

This XSS vulnerability stems from the renderFormField function in Beego's server/web/templatefunc.go file failing to properly sanitize user-controlled input before embedding it into HTML attributes. When developers use RenderForm() to dynamically generate form elements, any user-supplied values for parameters like id, class, name, or field values are directly interpolated into the HTML output without escaping.

The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation), which represents the canonical XSS weakness category. The network-based attack vector with no privileges required makes this vulnerability particularly dangerous, though it does require user interaction to trigger the malicious payload.

Root Cause

The root cause lies in the renderFormField function's direct string concatenation of user-controlled parameters into HTML attribute contexts without invoking template.HTMLEscapeString(). The function constructed HTML attributes like id=" + id + " and class=" + class + " directly from input parameters, allowing attackers to break out of attribute contexts and inject arbitrary JavaScript.

Attack Vector

An attacker can exploit this vulnerability by providing specially crafted input values that contain JavaScript payloads within form field parameters. When the application renders the form using RenderForm(), the malicious payload is embedded directly into the HTML output. When a victim views the page, the injected script executes in their browser context with full access to the session, cookies, and DOM.

Common attack scenarios include:

• Injecting event handlers via attribute breakout (e.g., " onclick="alert(1)" ")
• Stealing session cookies via document.cookie exfiltration
• Performing actions on behalf of authenticated users
• Redirecting users to malicious phishing pages

// renderFormField returns a string containing HTML of a single form field. In case of select fType, it will retrun
// select tag with options. Value for select fType must be comma separated string which are use are
func renderFormField(label, name, fType string, value interface{}, id string, class string, required bool) string {
	// Format attributes with spaces first
	idAttr := ""
	if id != "" {
		idAttr = " id=\"" + template.HTMLEscapeString(id) + "\""
	}

	classAttr := ""
	if class != "" {
		classAttr = " class=\"" + template.HTMLEscapeString(class) + "\""
	}

	requiredAttr := ""
	if required {
		requiredAttr = " required"
	}

	// Escape all string values
	escapedName := template.HTMLEscapeString(name)
	escapedLabel := template.HTMLEscapeString(label)
	escapedType := template.HTMLEscapeString(fType)

	// Handle value specially as it's an interface{}
	escapedValue := ""

Source: GitHub Commit Changes

Detection Methods for CVE-2025-30223

Indicators of Compromise

• Unusual JavaScript code appearing in form field attributes within application logs
• Client-side errors or unexpected script execution reported by users
• Suspicious outbound requests to unknown domains from client browsers
• Form submissions containing HTML special characters or JavaScript event handlers

Detection Strategies

• Review application logs for form inputs containing characters like <, >, ", ', or JavaScript event handlers (onclick, onerror, etc.)
• Implement Content Security Policy (CSP) headers and monitor for violations
• Deploy Web Application Firewall (WAF) rules to detect XSS payloads in request parameters
• Use browser-based XSS auditor alerts as an early warning mechanism

Monitoring Recommendations

• Enable verbose logging for all form submissions processed by RenderForm() functions
• Monitor for CSP violation reports that may indicate XSS exploitation attempts
• Track unusual patterns in user session behavior that could indicate hijacking
• Implement client-side integrity monitoring to detect unauthorized DOM modifications

How to Mitigate CVE-2025-30223

Immediate Actions Required

• Upgrade Beego to version 2.3.6 or later immediately
• Audit all uses of RenderForm() in your application codebase
• Implement input validation and output encoding as defense-in-depth measures
• Deploy Content Security Policy headers to mitigate potential exploitation

Patch Information

The vulnerability is fixed in Beego version 2.3.6. The patch adds proper HTML escaping using Go's template.HTMLEscapeString() function for all user-controlled values before they are embedded into HTML attributes. Review the GitHub Security Advisory GHSA-2j42-h78h-q4fg for complete details. The specific fix can be examined in the security patch commit.

Workarounds

• Manually escape all user-provided data before passing it to RenderForm() using html/template package functions
• Implement strict input validation to reject form data containing HTML special characters
• Use Content Security Policy headers with strict script-src directives to prevent inline script execution
• Consider implementing custom form rendering logic that enforces proper escaping until upgrade is possible

# Upgrade Beego to the patched version
go get -u github.com/beego/beego/v2@v2.3.6

# Verify the installed version
go list -m github.com/beego/beego/v2

# Update go.mod dependencies
go mod tidy