CVE-2026-34403

Nginx-UI vulnerable to Cross-Site WebSocket Hijacking (CSWSH) via missing origin validation on all WebSocket endpoints

Description

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.

Scores

Weaknesses (CWE)

• CWE-1385

Advisories

• GHSA-78mf-482w-62qj — Nginx-UI: Cross-Site WebSocket Hijacking (CSWSH) via missing origin validation on all WebSocket endpoints
• GO-2026-5210 — Nginx-UI: Cross-Site WebSocket Hijacking (CSWSH) via missing origin validation on all WebSocket endpoints in github.com/0xJacky/Nginx-UI

European references

• ENISA EUVD · EUVD-2026-23972
• GCVE · GCVE-0-2026-34403

Affected configurations (NVD CPE)

• cpe:2.3:a:nginxui:nginx_ui:*:*:*:*:*:*:*:* < 2.3.5

Affected products

References

• https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-78mf-482w-62qj
• https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.5

Sources