CVE-2025-58115: ChatLuck XSS Vulnerability in Guest Signup

CVE-2025-58115 Overview

CVE-2025-58115 is a cross-site scripting (XSS) vulnerability in the Guest User Sign-up functionality of ChatLuck, a business chat platform. The flaw allows an attacker to inject and execute arbitrary JavaScript in the browser of a user accessing the affected page. Exploitation requires user interaction, and the impact is limited to a subsequent system rather than the vulnerable application itself. The issue is classified under [CWE-79] Improper Neutralization of Input During Web Page Generation.

Critical Impact
An attacker can execute arbitrary script in a victim's browser session, enabling session data theft, credential harvesting through fake forms, and redirection to attacker-controlled infrastructure.

Affected Products

ChatLuck (Guest User Sign-up component)
Refer to the ChatLuck Support Package Issue advisory for exact affected versions
See the JVN Security Advisory for coordinated disclosure details

Discovery Timeline

2025-10-16 - CVE-2025-58115 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-58115

Vulnerability Analysis

The vulnerability resides in the Guest User Sign-up workflow of ChatLuck. User-supplied input submitted during the sign-up process is rendered back into a web page without adequate output encoding or input sanitization. An attacker crafts a malicious payload containing JavaScript and delivers it through a link or form interaction. When a victim accesses the affected page, the injected script executes in the context of the ChatLuck web application origin.

The attack requires user interaction, which aligns with a typical reflected XSS pattern. The vulnerability does not directly compromise the confidentiality, integrity, or availability of the vulnerable application, but it can affect a subsequent system by loading attacker-controlled content in the victim's browser.

Root Cause

The root cause is improper neutralization of untrusted input during web page generation [CWE-79]. The Guest User Sign-up handler accepts input intended for display or reflection and fails to apply context-aware encoding before writing it to the HTML response. Any characters with HTML or JavaScript significance, such as <, >, ", or ', are preserved and interpreted by the browser as executable markup.

Attack Vector

The attack is network-based and requires the victim to interact with an attacker-crafted request. A typical exploitation flow involves the attacker generating a URL or form submission that embeds a script payload targeting a vulnerable Guest User Sign-up parameter. The attacker distributes the link through phishing, chat messages, or embedded content. When the victim opens the link, the ChatLuck server reflects the payload into the response, and the browser executes the script under the ChatLuck origin.

The injected script can read DOM content presented to the guest sign-up user, submit forged forms, redirect the browser to attacker infrastructure, or render fake authentication prompts to harvest credentials. Because ChatLuck is a business chat platform, a successful attack against internal users can serve as a foothold for broader social engineering. No verified proof-of-concept code is publicly available for this issue.

Detection Methods for CVE-2025-58115

Indicators of Compromise

HTTP requests to the Guest User Sign-up endpoint containing script tags, event handlers such as onerror= or onload=, or encoded variants of <script>
Unexpected outbound connections from user browsers to external domains immediately after accessing ChatLuck sign-up pages
Reports from users of unexpected pop-ups, redirects, or fake login prompts on ChatLuck pages

Detection Strategies

Inspect web server and reverse-proxy logs for sign-up requests carrying HTML metacharacters or JavaScript keywords in query parameters and form fields
Deploy Web Application Firewall (WAF) rules that flag common XSS payload signatures such as javascript:, onerror, and document.cookie targeting ChatLuck URIs
Correlate browser telemetry with server-side sign-up events to identify script execution originating from ChatLuck responses

Monitoring Recommendations

Enable verbose logging on the ChatLuck web tier and forward logs to a centralized analytics platform for query and alerting
Monitor for anomalous referrer values and repeated sign-up attempts from the same source with varied payload structures
Track user reports of suspicious page behavior and correlate against recent access to guest sign-up URLs

How to Mitigate CVE-2025-58115

Immediate Actions Required

Apply the vendor patch referenced in the ChatLuck Support Package Issue advisory
Restrict or disable Guest User Sign-up until the fix is deployed, if the feature is not required
Educate users to avoid clicking untrusted links pointing to the ChatLuck sign-up flow

Patch Information

Refer to the vendor advisory published by the ChatLuck maintainers and the coordinated JVN Security Advisory for patched version details and upgrade instructions. Administrators should validate the deployed version against the vendor's fixed release before returning the Guest User Sign-up feature to production.

Workarounds

Enforce a strict Content Security Policy (CSP) that disallows inline scripts and restricts script sources to trusted origins
Place the ChatLuck front end behind a WAF configured with signatures for reflected XSS payloads
Set the HttpOnly and Secure flags on session cookies to reduce impact if a script executes in a user's browser

bash

# Example Nginx header hardening for the ChatLuck front end
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; frame-ancestors 'none'" always;
add_header X-Content-Type-Options "nosniff" always;
add_header X-Frame-Options "DENY" always;
add_header Referrer-Policy "no-referrer" always;