Overview
A critical security vulnerability, CVE-2025-9481, has been discovered in multiple Linksys range extender models. This vulnerability allows for a stack-based buffer overflow attack, potentially compromising the system and leading to data leakage. It’s a serious concern for any organization or individual using the affected models, as it opens the door for remote exploitation by attackers. The exploit has been publicly disclosed, and despite attempts at communication, the vendor has yet to respond.
Vulnerability Summary
CVE ID: CVE-2025-9481
Severity: Critical (8.8 CVSS Severity Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System Compromise and Data Leakage
Affected Products
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Product | Affected Versions
Linksys RE6250 | 1.0.013.001
Linksys RE6300 | 1.0.04.001
Linksys RE6350 | 1.0.04.002
Linksys RE6500 | 1.1.05.003
Linksys RE7000 | 1.2.07.001
Linksys RE9000 | 1.2.07.001
How the Exploit Works
The vulnerability exists in the function setIpv6 of the file /goform/setIpv6. The function does not correctly handle the argument tunrd_Prefix, leading to stack-based buffer overflow. An attacker can exploit this by sending a maliciously crafted request that contains an oversized tunrd_Prefix argument. When the function processes this argument, it overflows the buffer, which can lead to arbitrary code execution.
Conceptual Example Code
Here’s a conceptual example of how an attacker might exploit this vulnerability using an HTTP POST request. Note that this is a simplified representation and actual attacks may involve more complex payloads and methodologies.
POST /goform/setIpv6 HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
tunrd_Prefix=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA...In the above example, the tunrd_Prefix argument is filled with an excessive amount of “A” characters, which will overflow the buffer when processed by the setIpv6 function.
Mitigation Guidance
Until the vendor releases a patch, it is recommended to use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to mitigate this vulnerability. These solutions can help detect and block attempts to exploit this vulnerability. As a long-term solution, users are advised to apply the vendor patch as soon as it becomes available.
