CVE-2026-34403
Nginx-UI vulnerable to Cross-Site WebSocket Hijacking (CSWSH) via missing origin validation on all WebSocket endpoints
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.
INFO
Published Date :
April 20, 2026, 9:16 p.m.
Last Modified :
April 22, 2026, 5:35 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Nginx UI to version 2.3.5 or later.
- Configure CheckOrigin in WebSocket Upgrader.
- Implement HttpOnly and SameSite for cookies.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-34403.
| URL | Resource |
|---|---|
| https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.5 | Product Release Notes |
| https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-78mf-482w-62qj | Exploit Mitigation Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-34403 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-34403
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-34403 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-34403 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Apr. 22, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N Added CPE Configuration OR *cpe:2.3:a:nginxui:nginx_ui:*:*:*:*:*:*:*:* versions up to (excluding) 2.3.5 Added Reference Type GitHub, Inc.: https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.5 Types: Product, Release Notes Added Reference Type GitHub, Inc.: https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-78mf-482w-62qj Types: Exploit, Mitigation, Vendor Advisory -
New CVE Received by [email protected]
Apr. 20, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-1385 Added Reference https://github.com/0xJacky/nginx-ui/releases/tag/v2.3.5 Added Reference https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-78mf-482w-62qj