Nginx UI is a web user interface for the Nginx web server. Prior to version 2.3.5, all WebSocket endpoints in nginx-ui use a gorilla/websocket Upgrader with CheckOrigin unconditionally returning true, allowing Cross-Site WebSocket Hijacking (CSWSH). Combined with the fact that authentication tokens are stored in browser cookies (set via JavaScript without HttpOnly or explicit SameSite attributes), a malicious webpage can establish authenticated WebSocket connections to the nginx-ui instance when a logged-in administrator visits the attacker-controlled page. Version 2.3.5 patches the issue.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-1385"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34403.json"
}{
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "2.3.5"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"original_tag": "v2.3.5",
"range": [
{
"fixed": "1a9cd29a308278173aa0f16234cb78061dd2bd42"
}
],
"source": "REFERENCES_TAG"
},
{
"cpe": "cpe:2.3:a:nginxui:nginx_ui:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "2.3.5"
}
],
"source": "CPE_RANGE"
}
]
}