CVE-2025-8826 is a critical stack-based buffer overflow vulnerability affecting multiple Linksys range extender models, including RE6250, RE6300, RE6350, RE6500, RE7000, and RE9000, with firmware versions up to 20250801. The vulnerability resides in the function um_rp_autochannel within the /goform/RP_setBasicAuto endpoint. Specifically, the flaw is triggered by manipulating the arguments apcli_AuthMode_2G or apcli_AuthMode_5G, which leads to a stack-based buffer overflow condition. This type of vulnerability allows an attacker to overwrite memory on the stack, potentially enabling arbitrary code execution or causing a denial of service. The attack can be launched remotely without requiring user interaction or prior authentication, making it highly exploitable. The vendor, Linksys, was notified early but has not responded or issued a patch, and public exploit code has been disclosed, increasing the risk of exploitation. The vulnerability has a CVSS 4.0 base score of 8.7, indicating high severity, with network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability. The absence of a patch and public exploit availability make this vulnerability a significant threat to affected devices, which are commonly deployed in home and small office environments to extend wireless network coverage.

For European organizations, this vulnerability poses a substantial risk, particularly for small and medium enterprises (SMEs) and home office setups that rely on Linksys range extenders for network connectivity. Successful exploitation could allow attackers to execute arbitrary code remotely, leading to full compromise of the device. This can result in interception or manipulation of network traffic, lateral movement within the internal network, and disruption of wireless connectivity. Confidential information transmitted over the network could be exposed or altered, impacting data confidentiality and integrity. The availability of network services could also be disrupted, affecting business operations. Given the widespread use of Linksys devices in Europe and the lack of vendor response, organizations may face increased exposure to targeted attacks or opportunistic exploitation by cybercriminals. Additionally, the vulnerability could be leveraged as a foothold for more sophisticated attacks against critical infrastructure or sensitive data environments within European enterprises.

Immediate mitigation steps include isolating affected Linksys range extenders from critical network segments to limit potential lateral movement. Network administrators should monitor network traffic for unusual activity originating from or targeting these devices. Employ network segmentation and strict access controls to reduce exposure. Since no official patch is available, organizations should consider replacing vulnerable devices with models from vendors that provide timely security updates. If replacement is not immediately feasible, disabling remote management interfaces and restricting access to the /goform/RP_setBasicAuto endpoint via firewall rules can reduce attack surface. Regularly update network device inventories to identify all affected models and firmware versions. Implement intrusion detection/prevention systems (IDS/IPS) tuned to detect exploitation attempts targeting this vulnerability. Finally, maintain heightened awareness and readiness to respond to any signs of compromise related to these devices.