CVE-2026-34403

Summary

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 Software

Weaknesses

• CWE-1385: CWE-1385: Missing Origin Validation in WebSockets

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: no
  • Technical Impact: partial

References

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

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