CVE-2025-3899 Overview
CVE-2025-3899 is a stored cross-site scripting (XSS) vulnerability [CWE-79] in the Certificates page of an affected Schneider Electric webserver. An authenticated attacker can inject unvalidated data that executes in a victim's browser when the page is rendered. Successful exploitation allows the attacker to read or modify data within the victim's browser session, including content shown by the management interface.
The issue requires authenticated access and user interaction with the injected content. Schneider Electric published advisory SEVD-2025-161-02 describing the flaw and remediation guidance.
Critical Impact
An authenticated attacker can inject persistent script into the Certificates page, enabling browser-side data theft or modification against other users of the webserver.
Affected Products
- Schneider Electric product line covered by advisory SEVD-2025-161-02 (Webserver component with Certificates page)
- Specific product and firmware versions: refer to the Schneider Electric security notice
- No CPE entries were published in NVD at time of writing
Discovery Timeline
- 2025-06-10 - CVE-2025-3899 published to the National Vulnerability Database
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-3899
Vulnerability Analysis
The vulnerability resides in the Certificates page of the affected Schneider Electric webserver. Input submitted through certificate-related fields is stored and later rendered in the browser without proper output encoding. When another authenticated user loads the page, the injected payload executes in the browser context of the webserver's origin.
Because the payload runs in an authenticated session, it can access DOM content, read fields visible to the victim, and issue authenticated requests to the same webserver. The attack requires prior authentication and user interaction, which limits exposure to environments where multiple operators or administrators share the interface.
Root Cause
The root cause is improper neutralization of input during web page generation. The Certificates page accepts attacker-controlled data and echoes it into the response HTML without sufficient sanitization or context-appropriate encoding. This allows arbitrary HTML or JavaScript to be persisted and executed on subsequent page loads.
Attack Vector
An attacker with valid credentials to the webserver submits a crafted value through the Certificates page. When a victim later browses to the affected view, the malicious script executes in the victim's browser. The attacker can then manipulate the rendered UI, exfiltrate session data available to client-side scripts, or perform actions on behalf of the victim within the webserver interface.
No public proof-of-concept, exploit code, or in-the-wild exploitation has been documented. Detailed exploitation specifics are described in the Schneider Electric Security Notice.
Detection Methods for CVE-2025-3899
Indicators of Compromise
- Certificate records or related fields containing HTML tags, <script> elements, event handlers such as onerror= or onload=, or javascript: URIs.
- Unexpected outbound requests from operator browsers to attacker-controlled hosts after visiting the Certificates page.
- Anomalous configuration changes originating from operator sessions shortly after viewing the Certificates page.
Detection Strategies
- Review stored certificate metadata in the webserver for markup characters that should not be present in valid certificate fields.
- Inspect webserver access logs for POST requests to the Certificates page containing encoded angle brackets or script keywords.
- Correlate authenticated user sessions with subsequent unusual client-side activity such as unexpected form submissions or navigation.
Monitoring Recommendations
- Enable and centralize webserver audit logs covering authentication events and configuration changes on the Certificates page.
- Monitor for repeated administrative activity from a single account that touches certificate storage and management endpoints.
- Alert on browser network telemetry that shows requests from the management interface origin to unknown external domains.
How to Mitigate CVE-2025-3899
Immediate Actions Required
- Apply the remediation described in Schneider Electric advisory SEVD-2025-161-02 as soon as it is available for your product and firmware.
- Restrict administrative access to the webserver to trusted operators and enforce least privilege for accounts that can modify certificates.
- Audit existing certificate entries for suspicious content and remove any records containing HTML or script fragments.
Patch Information
Schneider Electric documents fixed versions and remediation steps in the SEVD-2025-161-02 Security Notice. Operators should consult the notice for exact firmware versions and upgrade procedures applicable to their deployment.
Workarounds
- Place the webserver on an isolated management network and block access from general-purpose corporate or internet-facing zones.
- Require multi-factor authentication and unique accounts for each operator to enable accountability and reduce shared-credential exposure.
- Instruct operators to access the webserver from a dedicated browser profile that does not store credentials or session data for other applications.
- Enforce a strict Content Security Policy at any reverse proxy in front of the webserver to limit inline script execution where feasible.
# Example: restrict management interface access at the network edge
# Replace 10.0.10.0/24 with the trusted operator subnet
iptables -A INPUT -p tcp --dport 443 -s 10.0.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.