# CVE-2026-34403: Nginx-UI: Cross-Site WebSocket Hijacking (CSWSH) via missing origin validation on all WebSocket endpoints

Source: https://junglewise.ai/threats/cve-2026-34403-nginx-ui-cross-site-websocket-hijacking-cswsh-via-missing-origin  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-20  
License: CC BY 4.0 with a link back

CVE-2026-34403 · Severity: high · CVSS 8.1 · Published 2026-04-20

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.

Technologies: [github.com/0xJacky/Nginx-UI (Go)](https://junglewise.ai/threats/technologies/github-com-0xjacky-nginx-ui), [Nginxui Nginx Ui](https://junglewise.ai/threats/technologies/nginxui-nginx-ui). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Nginxui](https://junglewise.ai/threats/vendors/nginxui).

## Quick answers

**Is CVE-2026-34403 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34403 being exploited in the wild.

**How severe is CVE-2026-34403?** High severity, with a CVSS score of 8.1, published 20 April 2026.

**Which products and versions are affected?** github.com/0xJacky/Nginx-UI (Go) SEMVER:introduced=0,fixed=1.9.10-0.20260316053337-1a9cd29a3082.

**Is there a fix for CVE-2026-34403?** Yes. github.com/0xJacky/Nginx-UI (Go): upgrade to 1.9.10-0.20260316053337-1a9cd29a3082 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-34403?** Check whether you run github.com/0xJacky/Nginx-UI (Go) or Nginxui Nginx Ui at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/0xJacky/Nginx-UI (Go): upgrade to 1.9.10-0.20260316053337-1a9cd29a3082 or later

  ```sh
  go get github.com/0xJacky/Nginx-UI@v1.9.10-0.20260316053337-1a9cd29a3082
  ```


## Affected products

- github.com/0xJacky/Nginx-UI (Go) SEMVER:introduced=0,fixed=1.9.10-0.20260316053337-1a9cd29a3082
- Nginxui Nginx Ui

## Identifiers

- CVE-2026-34403
- GHSA-78mf-482w-62qj
- GO-2026-5210

## Related threats

- [Nginx UI Casdoor SSO login CSRF via constant state parameter](https://junglewise.ai/threats/cve-2026-84312-nginx-ui-casdoor-sso-callback-uses-a-constant-state-parameter)
- [Nginx UI OTP secure-session step-up bypass via MCP](https://junglewise.ai/threats/cve-2026-84360-nginx-ui-otp-secure-session-step-up-can-be-bypassed-via-mcp)
- [Nginx UI short token cache bypass after account re-enable](https://junglewise.ai/threats/cve-2026-84321-nginx-ui-standalone-short-tokens-survive-administrative)
- [Nginx UI auto backup path traversal in storage boundary](https://junglewise.ai/threats/cve-2026-84320-nginx-ui-auto-backup-name-allows-path-traversal-outside-validated)
- [Nginx UI MCP configuration directive validation bypass](https://junglewise.ai/threats/cve-2026-84319-nginx-ui-mcp-configuration-tools-bypass-restricted-directive)