CVE-2025-46178: CloudClassroom PHP Project XSS Flaw

CVE-2025-46178 Overview

CVE-2025-46178 is a reflected Cross-Site Scripting (XSS) vulnerability in the CloudClassroom PHP Project version 1.0 by vishalmathur. The flaw resides in askquery.php and is triggered through the eid parameter, which fails to sanitize user-supplied input before echoing it into the HTML response. Remote attackers can craft a URL containing arbitrary JavaScript and deliver it to a victim through phishing or social engineering. When the victim loads the URL, the injected script executes in the browser under the origin of the CloudClassroom application, enabling session hijacking, defacement, or credential theft.

Critical Impact
A crafted URL executes attacker-controlled JavaScript in the victim's authenticated session, allowing cookie theft, account takeover, and page defacement.

Affected Products

vishalmathur CloudClassroom-PHP Project 1.0
All deployments serving askquery.php with the unpatched eid parameter
Downstream forks that inherit the vulnerable query handler

Discovery Timeline

2025-06-09 - CVE-2025-46178 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-46178

Vulnerability Analysis

The vulnerability is a classic reflected XSS issue tracked under [CWE-79] (Improper Neutralization of Input During Web Page Generation). The askquery.php endpoint accepts the eid HTTP GET parameter and reflects its value directly into the rendered HTML without applying output encoding or input filtering. Because the response reflects attacker input into an executable context, any browser rendering the page executes the injected payload.

Exploitation requires user interaction, since the victim must click a crafted link. The impact is scoped to the browser context, but a successful payload runs with full access to Document Object Model (DOM) resources, cookies not marked HttpOnly, and any session tokens exposed to JavaScript. Attackers commonly chain this into session hijacking against authenticated CloudClassroom instructors and students.

Root Cause

The root cause is missing input sanitization and output encoding on the eid GET parameter within askquery.php. The PHP handler concatenates the parameter into HTML output without invoking htmlspecialchars(), htmlentities(), or a context-aware templating engine. There is no allowlist validation on the parameter type or length.

Attack Vector

An attacker crafts a URL of the form http://<target>/askquery.php?eid=<script>...</script> and delivers it through email, chat, or a malicious referrer. When a logged-in user visits the URL, the browser executes the payload under the CloudClassroom origin. The Same-Origin Policy allows the script to read session cookies, exfiltrate them to an attacker-controlled server, submit forms on behalf of the user, or rewrite page content for phishing.

The vulnerability requires no authentication to exploit, and the changed scope means the injected script can affect data beyond the vulnerable component itself. See the GitHub proof-of-concept for CVE-2025-46178 for the payload structure.

Detection Methods for CVE-2025-46178

Indicators of Compromise

HTTP GET requests to askquery.php where the eid parameter contains <script>, onerror=, onload=, javascript:, or URL-encoded equivalents such as %3Cscript%3E
Outbound browser requests to unfamiliar domains immediately following a visit to askquery.php
Session cookies observed in query strings, Referer headers, or POST bodies to external hosts
Web server access logs showing long or obfuscated eid parameter values from a single referrer chain

Detection Strategies

Deploy Web Application Firewall (WAF) rules that inspect the eid parameter for HTML tags, event handlers, and JavaScript URI schemes
Enable Content Security Policy (CSP) reporting to capture blocked inline script executions on the CloudClassroom origin
Correlate reflected parameter values in access logs against known XSS payload signatures using regex matching

Monitoring Recommendations

Alert on any askquery.php request where the eid parameter length exceeds a defined baseline or contains angle brackets
Monitor endpoint browsers for anomalous DOM modifications and unauthorized cookie exfiltration attempts
Review authentication logs for session reuse from multiple IP addresses, which can indicate cookie theft following XSS exploitation

How to Mitigate CVE-2025-46178

Immediate Actions Required

Restrict access to askquery.php behind authentication or a WAF rule that strips HTML metacharacters from the eid parameter
Set the HttpOnly and Secure flags on all session cookies to reduce the impact of a successful XSS payload
Deploy a strict Content Security Policy that disallows inline scripts and untrusted script sources
Audit web server logs for prior exploitation attempts targeting the eid parameter

Patch Information

No official vendor patch has been published for the CloudClassroom PHP Project at the time of this advisory. Administrators should apply source-level fixes by encoding the eid parameter with htmlspecialchars($_GET['eid'], ENT_QUOTES, 'UTF-8') before rendering, and validating the parameter against an expected format such as a numeric identifier. Refer to the public advisory for CVE-2025-46178 for technical details.

Workarounds

Filter requests at the reverse proxy or WAF layer to reject eid values containing <, >, ", ', or javascript:
Disable or remove askquery.php if the query submission feature is not required in production
Enforce Subresource Integrity (SRI) and CSP directives to block unauthorized inline script execution

bash

# Example nginx configuration to block XSS payloads in the eid parameter
location /askquery.php {
    if ($arg_eid ~* "(<|>|script|onerror|onload|javascript:)") {
        return 403;
    }
    add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'";
    add_header X-XSS-Protection "1; mode=block";
    add_header X-Content-Type-Options "nosniff";
}