CVE-2026-34403
Nginx-UI vulnerable to Cross-Site WebSocket Hijacking (CSWSH) via missing origin validation on all WebSocket endpoints
- State
- Published
- Severity
- 5.5 Medium
- Published
- Apr 20, 2026
- Updated
- Apr 21, 2026
- Reserved
- Mar 27, 2026
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
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.5 Medium | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P | GitHub_M |
Weaknesses
- CWE-1385 Missing Origin Validation in WebSockets
Affected Products
| Product | Versions |
|---|---|
nginx-ui0xJacky |
|
References
Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.