Vulnerability · Published Apr 20, 2026 · Assigned by GitHub_M

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

Medium 5.5

In plain English

A medium-severity security flaw in nginx-ui from 0xJacky. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)5.5Medium

Exploit odds (30 days)0.2%top 92.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/0xJacky/Nginx-UI	1.9.10-0.20260316053337-1a9cd29a3082	GO-2026-5210
Go	github.com/0xJacky/Nginx-UI	1.9.10-0.20260316053337-1a9cd29a3082	GHSA-78mf-482w-62qj

Affected products (as reported)

Vendor	Product	Versions
0xJacky	nginx-ui	< 2.3.5

Weakness: CWE-1385 · Vector: 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

References

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