CVE-2026-1156 identifies a buffer overflow vulnerability in the Totolink LR350 router firmware version 9.3.5u.6369_B20220309. The vulnerability resides in the setWiFiBasicCfg function of the /cgi-bin/cstecgi.cgi script, which processes the ssid parameter. Due to insufficient bounds checking, an attacker can craft a specially malformed ssid argument that overflows the buffer, potentially overwriting adjacent memory. This flaw is exploitable remotely over the network without requiring authentication or user interaction, making it highly accessible to attackers. The consequences of successful exploitation include remote code execution, allowing attackers to take full control of the device, or denial of service by crashing the router. The CVSS v4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, combined with the ease of exploitation (network vector, no privileges or user interaction needed). Although no active exploits have been reported in the wild, public disclosure of exploit code increases the likelihood of future attacks. The affected product, Totolink LR350, is a widely used consumer and small business router, often deployed in European homes and offices, making this vulnerability a significant threat to network security. The lack of available patches at the time of disclosure necessitates immediate mitigation efforts to reduce exposure.

The impact of CVE-2026-1156 on European organizations can be severe. Successful exploitation allows attackers to execute arbitrary code remotely on affected routers, potentially leading to full device compromise. This can result in interception or manipulation of network traffic, unauthorized access to internal networks, and disruption of internet connectivity. Confidentiality is at risk as attackers could eavesdrop on sensitive communications or redirect traffic to malicious endpoints. Integrity may be compromised through unauthorized configuration changes or injection of malicious firmware. Availability could be affected by denial of service conditions caused by crashes or resource exhaustion. Organizations relying on Totolink LR350 routers for critical connectivity, including small and medium enterprises and home offices, face increased risk of data breaches, espionage, and operational disruption. The public disclosure of exploit code further elevates the threat level, increasing the likelihood of automated attacks targeting vulnerable devices across Europe.

To mitigate CVE-2026-1156, European organizations should take the following specific actions: 1) Immediately restrict remote access to the router's management interface by disabling WAN-side access or implementing strict firewall rules to limit access to trusted IP addresses only. 2) Monitor network traffic for unusual or malformed HTTP requests targeting /cgi-bin/cstecgi.cgi, particularly those containing suspicious ssid parameters, using intrusion detection systems or network monitoring tools. 3) Where possible, isolate vulnerable Totolink LR350 devices on segmented networks to limit lateral movement in case of compromise. 4) Regularly check for and apply firmware updates from Totolink as soon as patches addressing this vulnerability become available. 5) Consider replacing affected devices with models from vendors that provide timely security updates and have a strong security track record. 6) Educate IT staff and users about the risks of using default or outdated router firmware and the importance of secure configuration. These targeted measures go beyond generic advice by focusing on access control, monitoring, network segmentation, and proactive patch management specific to this vulnerability and product.