CVE-2026-1158 is a buffer overflow vulnerability identified in the Totolink LR350 router firmware version 9.3.5u.6369_B20220309. The vulnerability resides in the setWizardCfg function of the /cgi-bin/cstecgi.cgi component, which handles POST requests. Specifically, the flaw arises from improper handling of the 'ssid' argument, where crafted input can overflow a buffer, leading to memory corruption. This type of vulnerability can allow remote attackers to execute arbitrary code on the device without requiring authentication or user interaction. The attack vector is network-based, as the vulnerable CGI endpoint is exposed to remote requests. The CVSS 4.0 base score is 8.7, indicating high severity, with the vector string showing network attack vector, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. Although no exploits have been observed in the wild, a public exploit has been released, increasing the risk of exploitation. The vulnerability affects a specific firmware version, so devices running other versions may not be vulnerable. The lack of vendor patch links suggests that a fix may not yet be available, emphasizing the need for interim mitigations. This vulnerability is critical because routers like the LR350 are often used in enterprise and small-to-medium business environments, and compromise could lead to network-wide breaches or persistent attacker footholds.

For European organizations, exploitation of this vulnerability could lead to severe consequences including unauthorized access to internal networks, interception or manipulation of sensitive data, disruption of network services, and potential lateral movement within corporate environments. Given the router’s role as a network gateway, a successful attack could compromise confidentiality, integrity, and availability of organizational data and systems. This is particularly concerning for sectors such as finance, healthcare, government, and critical infrastructure where network reliability and data security are paramount. The remote and unauthenticated nature of the exploit increases the attack surface, potentially allowing widespread automated attacks if the exploit is weaponized. Additionally, organizations with remote or hybrid workforces relying on these routers for VPN or secure connectivity may face increased risk. The absence of a patch at the time of disclosure means organizations must rely on network-level controls to mitigate risk, which may not be fully effective if the device is directly exposed to the internet.

1. Immediately inventory and identify all Totolink LR350 devices running firmware version 9.3.5u.6369_B20220309 within the network. 2. Monitor vendor communications closely for official patches or firmware updates addressing CVE-2026-1158 and apply them promptly once available. 3. Until patches are released, restrict access to the vulnerable device’s management interfaces by implementing network segmentation and firewall rules to block incoming traffic to /cgi-bin/cstecgi.cgi endpoints from untrusted networks. 4. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting exploit attempts targeting this vulnerability. 5. Disable remote management features on affected devices if not required, or restrict management access to trusted IP addresses only. 6. Conduct regular network traffic analysis to detect anomalous POST requests targeting the vulnerable CGI endpoint. 7. Consider replacing affected devices with alternative hardware if patching is delayed or not feasible. 8. Educate IT staff on the risks and signs of exploitation related to this vulnerability to ensure rapid incident response. 9. Implement strong network segmentation to limit potential lateral movement in case of compromise. 10. Maintain up-to-date backups and incident response plans tailored to network device compromise scenarios.