CVE-2026-1157 is a buffer overflow vulnerability discovered in the Totolink LR350 router firmware version 9.3.5u.6369_B20220309. The flaw exists in the setWiFiEasyCfg function within the /cgi-bin/cstecgi.cgi endpoint, specifically in the handling of the ssid parameter. An attacker can remotely send a specially crafted request to this CGI script, causing a buffer overflow due to insufficient input validation or improper memory handling. This overflow can corrupt memory, potentially allowing arbitrary code execution or denial of service. The vulnerability requires no user interaction and no prior authentication, making it remotely exploitable over the network. The CVSS 4.0 score is 8.7 (high), reflecting the ease of exploitation (network attack vector, low attack complexity), no privileges required, and the high impact on confidentiality, integrity, and availability. Although no active exploitation in the wild has been reported, a public exploit is available, increasing the urgency for mitigation. The vulnerability affects a specific firmware version, so other versions may not be vulnerable. The lack of vendor patches at the time of disclosure necessitates interim defensive measures. This vulnerability poses a significant risk to networks using the Totolink LR350 router, especially in environments where these devices are exposed to untrusted networks or the internet.

The impact of CVE-2026-1157 is significant for organizations using the affected Totolink LR350 firmware. Successful exploitation can lead to arbitrary code execution on the router with elevated privileges, allowing attackers to take full control of the device. This can result in interception or manipulation of network traffic, deployment of persistent backdoors, disruption of network availability, and pivoting to internal networks for further compromise. Confidentiality of sensitive data passing through the router can be compromised, and integrity of network configurations can be altered maliciously. The availability of the network can also be impacted if the device is crashed or rebooted by the exploit. Since the vulnerability requires no authentication and no user interaction, it can be exploited by remote attackers scanning for vulnerable devices, increasing the risk of widespread attacks. Organizations relying on these routers for critical connectivity or security functions face elevated risks of operational disruption and data breaches.

1. Immediately restrict access to the router’s management interface by implementing network segmentation and firewall rules to limit access to trusted IP addresses only. 2. Disable remote management features if not required to reduce exposure to external attackers. 3. Monitor network traffic for unusual requests targeting /cgi-bin/cstecgi.cgi or anomalous ssid parameter values indicative of exploitation attempts. 4. Apply any vendor-released firmware updates or patches addressing this vulnerability as soon as they become available. 5. If patches are unavailable, consider replacing affected devices with models not impacted by this vulnerability or deploying compensating controls such as intrusion prevention systems (IPS) with signatures targeting this exploit. 6. Conduct regular vulnerability scans and penetration tests to identify and remediate similar issues proactively. 7. Educate network administrators about this vulnerability and ensure incident response plans include steps for containment and recovery from router compromises.