CVE-2025-29231 is a stored cross-site scripting vulnerability identified in the Linksys E5600 router firmware version 1.1.0.26, specifically within the page_save component. The vulnerability arises from improper sanitization of user-supplied input in the hostname and domainName parameters, which are used in the router's web management interface. An attacker can craft a malicious payload that, when injected into these parameters, is stored persistently on the device. When an administrator or user accesses the affected page, the malicious script executes in their browser context, enabling actions such as session hijacking, credential theft, or further exploitation of the internal network. Stored XSS is particularly dangerous because the payload remains on the device and can affect multiple users over time. The vulnerability does not require user interaction beyond visiting the affected page, and no authentication bypass is indicated, but the attacker must be able to submit data to the vulnerable parameters, which may require some level of access to the device's web interface or network. No patches or exploits are currently documented, but the risk remains significant given the critical role of routers in network security and management. The absence of a CVSS score necessitates a severity assessment based on the vulnerability's characteristics and potential impact.

For European organizations, this vulnerability could lead to unauthorized access to router management interfaces, enabling attackers to alter network configurations, intercept or redirect traffic, and compromise internal systems. The exploitation of stored XSS on routers can facilitate lateral movement within corporate networks and undermine trust in network infrastructure. Given the widespread use of Linksys devices in small to medium enterprises and home offices across Europe, the potential impact includes data breaches, disruption of business operations, and exposure of sensitive information. Critical sectors such as finance, healthcare, and government agencies relying on affected devices for network connectivity are particularly vulnerable. The persistence of the stored XSS payload increases the risk of prolonged exploitation and complicates detection and remediation efforts. Additionally, attackers could leverage this vulnerability to deploy further malware or conduct phishing attacks targeting network administrators.

Organizations should immediately review and restrict access to the Linksys E5600 router management interface, disabling remote management where possible to reduce exposure. Network segmentation should be enforced to limit access to router interfaces only to trusted administrators. Monitoring network traffic and router logs for unusual activity or unauthorized configuration changes can help detect exploitation attempts. Until an official patch is released, consider implementing web application firewalls (WAFs) or intrusion prevention systems (IPS) that can detect and block XSS payloads targeting the router interface. Educate network administrators about the risks of stored XSS and the importance of cautious input handling. If feasible, replace vulnerable devices with updated hardware or firmware versions that address this vulnerability. Regularly check vendor advisories for patches or updates and apply them promptly. Additionally, conduct security audits focusing on router configurations and access controls to minimize attack surfaces.