CVE-2025-27379: Altium AES BOM Viewer XSS Vulnerability

CVE-2025-27379 Overview

A stored cross-site scripting (XSS) vulnerability has been identified in the BOM Viewer component of Altium AES 7.0.3. This vulnerability allows an authenticated attacker to inject arbitrary JavaScript code into the Description field of a schematic. When the BOM Viewer renders the affected content, the malicious script is executed in the context of other users' browser sessions, potentially leading to session hijacking, data theft, or further attacks on connected systems.

Critical Impact

Authenticated attackers can inject persistent malicious JavaScript that executes in victims' browsers when viewing BOM content, potentially compromising user sessions and sensitive design data.

Affected Products

• Altium AES 7.0.3
• BOM Viewer component in affected Altium AES versions

Discovery Timeline

• 2026-01-22 - CVE CVE-2025-27379 published to NVD
• 2026-01-22 - Last updated in NVD database

Technical Details for CVE-2025-27379

Vulnerability Analysis

This stored XSS vulnerability (CWE-79) exists within the BOM Viewer functionality of Altium AES. The vulnerability arises from insufficient input validation and output encoding when processing user-supplied content in schematic Description fields. When an authenticated user with appropriate permissions creates or modifies a schematic, they can embed malicious JavaScript payloads within the Description field. These payloads persist in the application's database and are subsequently executed whenever another user views the affected content through the BOM Viewer interface.

The attack requires authentication to inject the malicious payload, but victim interaction is necessary for exploitation—specifically, the victim must view the compromised BOM content. This combination of requirements limits the initial attack surface but enables persistent attacks against multiple users over time.

Root Cause

The root cause of CVE-2025-27379 is improper neutralization of input during web page generation. The BOM Viewer fails to properly sanitize or encode user-controlled input from the Description field before rendering it in the browser. This allows specially crafted HTML and JavaScript content to be interpreted as executable code rather than being displayed as plain text.

The lack of Content Security Policy (CSP) headers or other browser-side security controls may further exacerbate the impact of this vulnerability by allowing injected scripts to execute without restriction.

Attack Vector

The attack vector for this vulnerability is network-based and requires an authenticated attacker with permissions to modify schematic Description fields. The exploitation process involves:

1. An authenticated attacker accesses the schematic editing functionality
2. The attacker injects malicious JavaScript code into the Description field of a schematic component
3. The payload is stored in the application database
4. When any user views the affected content through the BOM Viewer, the malicious script executes in their browser context
5. The attacker can then steal session tokens, capture keystrokes, redirect users to malicious sites, or perform actions on behalf of the victim

The stored nature of this XSS vulnerability makes it particularly dangerous as the payload persists and can affect multiple users without requiring the attacker to maintain an active presence.

Detection Methods for CVE-2025-27379

Indicators of Compromise

• Unusual JavaScript or HTML tags present in schematic Description fields
• Browser developer console errors or warnings related to Content Security Policy violations
• Unexpected network requests originating from the BOM Viewer interface to external domains
• User reports of unusual behavior when viewing BOM content

Detection Strategies

• Implement web application firewall (WAF) rules to detect XSS payloads in HTTP requests targeting schematic modification endpoints
• Deploy endpoint detection and response (EDR) solutions to monitor browser behavior for suspicious script execution patterns
• Review application logs for unusual patterns in Description field modifications
• Conduct regular database scans to identify stored XSS payloads in schematic data

Monitoring Recommendations

• Enable verbose logging on the Altium AES application server to capture all schematic modification events
• Configure SIEM alerts for patterns consistent with XSS injection attempts in user input fields
• Monitor outbound network traffic from client workstations accessing the BOM Viewer for connections to unknown external domains
• Implement user behavior analytics to detect anomalous editing patterns that may indicate exploitation attempts

How to Mitigate CVE-2025-27379

Immediate Actions Required

• Review and audit all existing schematic Description fields for potentially malicious content
• Restrict access to schematic modification features to trusted users only
• Implement network segmentation to limit the potential impact of compromised sessions
• Educate users about the risk and advise caution when viewing BOM content from untrusted sources

Patch Information

Consult the Altium Security Advisories page for official patch information and updated versions that address this vulnerability. Organizations should prioritize upgrading to a patched version of Altium AES as soon as one becomes available.

Workarounds

• Implement strict Content Security Policy (CSP) headers at the web server or reverse proxy level to prevent inline script execution
• Deploy a web application firewall (WAF) with XSS protection rules in front of the Altium AES application
• Restrict schematic editing permissions to a minimal set of trusted users until a patch is available
• Consider disabling the BOM Viewer feature temporarily if the business impact is acceptable

# Example CSP header configuration for Apache
# Add to httpd.conf or .htaccess for Altium AES virtual host
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; object-src 'none';"