CVE-2026-34403 Nginx-UI vulnerable to Cross-Site WebSocket Hijacking (CSWSH) via missing origin validation on all WebSocket endpoints
Attackers can hijack authenticated WebSocket sessions via CSRF, potentially leading to account takeover or code execution on the Nginx UI.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-34403?
CVE-2026-34403 is a medium-severity vulnerability in 0xJacky nginx-ui, published on 20 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-1385
Which versions are affected by CVE-2026-34403?
3 open source packages ship an affected version, including github.com/0xJacky/Nginx-UI. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/0xJacky/Nginx-UI Go | All versions | 1.9.10-0.20260316053337-1a9cd29a3082 |
github.com/0xJacky/Nginx-UI Go | All versions | 1.9.10-0.20260316053337-1a9cd29a3082 |
github.com/0xJacky/Nginx-UI Go | All versions | 1.9.10-0.20260316053337-1a9cd29a3082 |
Products include Nginxui Nginx Ui.
How do I fix CVE-2026-34403?
Upgrade github.com/0xJacky/Nginx-UI to 1.9.10-0.20260316053337-1a9cd29a3082 or later.
Is CVE-2026-34403 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34403 exists.
Other vulnerabilities in 0xJacky nginx-ui
- CVE-2026-33032 Nginx UI: Unauthenticated MCP Endpoint Allows Remote Nginx Takeover
- CVE-2026-27944 Nginx UI: Unauthenticated Backup Download with Encryption Key Disclosure
- CVE-2024-23827 Nginx-UI arbitrary file write through the Import Certificate feature
- CVE-2026-107806 Nginx UI: Authenticated Remote Code Execution via Backup Restore App Config Overwrite
- CVE-2026-33026 nginx-ui Backup Restore Allows Tampering with Encrypted Backups
Sources
Also known as GHSA-78mf-482w-62qj, GO-2026-5210.