CVE-2026-34805 is a stored cross-site scripting vulnerability (CWE-79) affecting Endian Firewall version 3.3.25 and prior. The vulnerability exists due to improper neutralization of input in the remark parameter of the /cgi-bin/dnat.cgi endpoint. An attacker with authentication privileges can inject arbitrary JavaScript code that is stored on the server and executed in the browsers of other users viewing the affected page. This can lead to client-side script execution under the context of the vulnerable application.

Successful exploitation allows an authenticated attacker to execute arbitrary JavaScript in the context of other users' browsers when they view the affected page. This can lead to session hijacking, unauthorized actions, or other client-side impacts typical of stored XSS vulnerabilities. The CVSS 4.0 score of 5.1 reflects a medium severity impact with network attack vector, low attack complexity, and requiring privileges and user interaction.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch or official fix information is provided, users should monitor the vendor's communications for updates. Until a fix is available, limit access to the affected functionality to trusted users and consider additional input validation or filtering on the remark parameter if possible.