Overview
A critical security vulnerability, identified as CVE-2025-6752, has been discovered affecting several Linksys router models, including WRT1900ACS, EA7200, EA7450, and EA7500 up to 20250619. This vulnerability has been classified as critical due to its potential to compromise systems and leak data. This vulnerability is particularly concerning as it affects the function SetDefaultConnectionService of the file /upnp/control/Layer3Forwarding of the IGD component and can be exploited remotely. The exploit is publicly disclosed, and the vendor has yet to respond.
Vulnerability Summary
CVE ID: CVE-2025-6752
Severity: Critical (8.8 CVSS score)
Attack Vector: Remote
Privileges Required: None
User Interaction: None
Impact: Potential system compromise and data leakage
Affected Products
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Product | Affected Versions
Linksys WRT1900ACS | Up to 20250619
Linksys EA7200 | Up to 20250619
Linksys EA7450 | Up to 20250619
Linksys EA7500 | Up to 20250619
How the Exploit Works
The vulnerability comes into play when an attacker manipulates the argument NewDefaultConnectionService, leading to a stack-based buffer overflow. This overflow then can cause the system to crash or, worse, allow the attacker to execute arbitrary code on the system. This exploitation can be initiated remotely, making it a significant threat to any unprotected networks.
Conceptual Example Code
Below is a conceptual example of how an HTTP request exploiting this vulnerability might look:
POST /upnp/control/Layer3Forwarding HTTP/1.1
Host: target_router_IP
Content-Type: application/xml; charset="utf-8"
SOAPAction: "urn:schemas-upnp-org:service:Layer3Forwarding:1#SetDefaultConnectionService"
<?xml version="1.0"?>
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
<s:Body>
<u:SetDefaultConnectionService xmlns:u="urn:schemas-upnp-org:service:Layer3Forwarding:1">
<NewDefaultConnectionService>[malicious_code]</NewDefaultConnectionService>
</u:SetDefaultConnectionService>
</s:Body>
</s:Envelope>In this example, the [malicious_code] placeholder would be replaced with the actual code designed to overflow the buffer.
Recommended Mitigation
Until the vendor releases a patch to fix this vulnerability, users are advised to apply a Web Application Firewall (WAF) or Intrusion Detection System (IDS) as a temporary mitigation. These solutions can help detect and block malicious activities related to this vulnerability. Furthermore, users should regularly monitor their network for any unusual activities.