# CVE-2026-34403

## Summary

- **CVE ID:** CVE-2026-34403
- **Severity:** MEDIUM
- **CVSS Score:** 5.5 (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)
- **CWE:** CWE-1385
- **Published:** Apr 20, 2026
- **Last Modified:** Apr 21, 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.

## Affected Products

- 0xJacky — nginx-ui (< 2.3.5)

## References

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

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.18%
- **EPSS Percentile:** 7.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._