CVE-2025-50740 is a cross-site scripting (XSS) vulnerability identified in AutoConnect version 1.4.2, an Arduino library commonly used to facilitate Wi-Fi connectivity in embedded IoT devices. The vulnerability exists in the AutoConnect web interface endpoint /_ac/config, which processes network SSID values. Specifically, the interface fails to properly sanitize or encode SSID inputs, allowing an attacker to inject crafted HTML or JavaScript code. When a victim accesses the vulnerable web interface, the malicious script executes in the context of the user's browser session. This can lead to theft of session tokens, redirection to malicious sites, or execution of arbitrary scripts. The CVSS v3.1 base score is 6.1 (medium severity), reflecting that the vulnerability is remotely exploitable over the network without authentication (AV:N, PR:N), but requires user interaction (UI:R) to trigger the malicious payload. The scope is changed (S:C), indicating that exploitation can affect components beyond the vulnerable interface, and the impact on confidentiality and integrity is low (C:L, I:L), with no impact on availability (A:N). No known exploits are currently reported in the wild, and no patches have been published yet. The vulnerability is classified under CWE-79, which corresponds to improper neutralization of input during web page generation leading to XSS. Given the nature of the vulnerability, it primarily affects devices using the AutoConnect library with exposed web interfaces that allow configuration via SSID input, typically IoT devices based on Arduino platforms.

For European organizations, the impact of this vulnerability depends largely on the deployment scale of IoT devices using the AutoConnect library. Many industrial, commercial, and smart building systems in Europe utilize Arduino-based devices for automation and monitoring. Exploitation of this XSS vulnerability could allow attackers to execute malicious scripts in the context of administrative or user web sessions, potentially leading to credential theft, session hijacking, or further network reconnaissance. While the direct impact on device availability is minimal, the compromise of web interface sessions could facilitate lateral movement or data exfiltration within corporate networks. This is particularly concerning for sectors with critical infrastructure or sensitive data, such as manufacturing, energy, healthcare, and smart city deployments. The requirement for user interaction means phishing or social engineering may be necessary, but the remote network attack vector increases the attack surface. Additionally, the scope change indicates that exploitation could affect other components or services linked to the vulnerable interface, amplifying potential damage. The lack of patches and known exploits suggests a window of exposure, and organizations relying on these devices should consider the risk in their IoT security posture.

To mitigate this vulnerability, European organizations should first inventory all IoT devices and embedded systems using the AutoConnect 1.4.2 library or similar versions. Since no official patches are currently available, immediate mitigation includes restricting access to the vulnerable web interface by network segmentation and firewall rules, limiting exposure to trusted networks only. Implementing web application firewalls (WAFs) that can detect and block XSS payloads targeting the /_ac/config endpoint can provide additional protection. Administrators should enforce strong authentication and session management controls on the device interfaces to reduce the risk of session hijacking. User awareness training to recognize phishing attempts that could trigger the XSS is also recommended. Where possible, organizations should consider disabling or replacing the vulnerable web interface or upgrading to a future patched version once available. Monitoring network traffic for unusual activity related to these devices and logging access attempts can help detect exploitation attempts early. Finally, engaging with device vendors or open-source maintainers to prioritize patch development is critical for long-term remediation.