Introduction
Remote attackers can run code on Linksys RE series range extenders by exploiting a stack-based buffer overflow in the device's remote management interface. The flaw affects a wide range of models used to extend Wi-Fi coverage in homes and small businesses. It takes no authentication to exploit, and it remains unpatched as of publication, which leaves many networks exposed.
Linksys sells into the consumer and SMB networking market, with millions of devices deployed worldwide, and the RE series range extenders are a common way to stretch wireless coverage. The company's security record for embedded firmware has been mixed, with several high-impact vulnerabilities reported in recent years.
Technical Information
CVE-2025-8831 is a stack-based buffer overflow in the remoteManagement function of Linksys RE6250, RE6300, RE6350, RE6500, RE7000, and RE9000 range extenders running firmware up to 20250801. The trigger is the /goform/remoteManagement endpoint, through the portNumber parameter. The firmware does not validate the length of portNumber before copying it into a stack-allocated buffer. By sending an HTTP POST request with an overly long portNumber value, an attacker can overwrite stack memory, including the return address, and execute arbitrary code as the web server process.
The root cause is improper input validation and unsafe memory handling in the embedded C code. It is a textbook case of CWE-119 and CWE-121: untrusted input copied into a fixed-size buffer with no bounds checking. The attack needs no authentication and works remotely whenever the management interface is reachable.
No vendor patch or mitigation is available as of this writing. The vendor was contacted before public disclosure but did not respond.
Proof of Concept
The Proof-of-Concept (PoC) exploit for CVE-2025-8831 targets the stack-based buffer overflow in Linksys range extenders, specifically models RE6250, RE6300, RE6350, RE6500, RE7000, and RE9000, with firmware versions up to 20250801. The flaw sits in the /goform/remoteManagement endpoint, where the portNumber parameter can be manipulated.
By sending a crafted HTTP request to this endpoint, an attacker can feed an overly long string into the portNumber parameter. That input overflows the buffer on the stack and can lead to arbitrary code execution. The exploit runs remotely, so an unauthenticated attacker can compromise the device without physical access.
The PoC shows that an attacker can execute arbitrary commands on the affected device and take control of it. From there, the attacker can reach the rest of the network, intercept data, or spread further.
The vendor was contacted about this vulnerability but did not respond, so the devices remain unpatched and open to exploitation.
Affected Systems and Versions
The following Linksys range extenders are affected:
- RE6250 (firmware up to 20250801)
- RE6300 (firmware up to 20250801)
- RE6350 (firmware up to 20250801)
- RE6500 (firmware up to 20250801)
- RE7000 (firmware up to 20250801)
- RE9000 (firmware up to 20250801)
Any configuration that exposes the /goform/remoteManagement endpoint is vulnerable. Remote management does not need to be enabled for the attack to succeed, as long as the endpoint is reachable.
Vendor Security History
Linksys has a history of memory safety and command injection bugs in its embedded products, especially in the RE series range extenders. Recent CVEs include several buffer overflows and command injection flaws in similar endpoints and parameters. The vendor's response to coordinated disclosure has been inconsistent, with repeated reports of non-responsiveness and delayed patching. Security maturity for this product line sits below the industry average.
