Vulnerability in 0xjacky Nginx-Ui
CVE-2026-34403
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (11.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 12th percentile — 11.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
- 0xjacky Nginx-Ui — versions < 2.3.5
- Nginxui nginx Ui
Weakness classification (CWE)
References
- github.com/0xJacky/nginx-ui/security/advisories/GHSA-78mf-482w-62qj (Exploit, Mitigation, Vendor Advisory)
- github.com/0xJacky/nginx-ui/releases/tag/v2.3.5 (Product, Release Notes)
Frequently asked questions
- What is CVE-2026-34403?
- CVE-2026-34403 is a high-severity vulnerability in 0xjacky Nginx-Ui, classified under CWE-1385. CVSS score: 8.1/10. Published 2026-04-20.
- How severe is CVE-2026-34403?
- High severity. CVSS v3 base score is 8.1 out of 10.