Overview
A critical vulnerability, identified as CVE-2025-8816, has been identified in several models of Linksys range extenders. This vulnerability is present in the setOpMode function of the /goform/setOpMode file, which can lead to a stack-based buffer overflow when manipulated via the argument ‘ethConv’. This vulnerability poses a significant threat due to its potential to compromise systems or leak data. The issue affects a wide array of Linksys devices, thereby posing a risk to a large number of users worldwide.
The vulnerability is particularly concerning as it can be exploited remotely, and the details of the exploit have been publicly disclosed. Despite being notified, the vendor has not responded to this disclosure, increasing the urgency of addressing this vulnerability.
Vulnerability Summary
CVE ID: CVE-2025-8816
Severity: Critical (8.8 CVSS 3.x Severity Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage
Affected Products
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Product | Affected Versions
Linksys RE6250 | up to 20250801
Linksys RE6300 | up to 20250801
Linksys RE6350 | up to 20250801
Linksys RE6500 | up to 20250801
Linksys RE7000 | up to 20250801
Linksys RE9000 | up to 20250801
How the Exploit Works
The vulnerability lies in the setOpMode function of the /goform/setOpMode file. An attacker can manipulate the ‘ethConv’ argument to trigger a buffer overflow. Buffer overflow occurs when more data is put into a buffer than it can handle, causing it to overwrite adjacent memory areas, leading to erratic program behavior, including memory access errors, incorrect results, program termination, or a breach of system security.
Conceptual Example Code
The following is a conceptual example of how the vulnerability might be exploited using an HTTP POST request to the vulnerable endpoint:
POST /goform/setOpMode HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
ethConv=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA...In this example, the ‘ethConv’ argument is filled with an excessively long string of ‘A’ characters, causing a buffer overflow and potentially allowing for the execution of malicious code.