CVE-2026-34403: Nginx UI is a web user interface for the Nginx web server

Q: How do I fix CVE-2026-34403?

nginx ui: upgrade to 2.3.5. Exact commands for each OS are on this page.

Q: Is CVE-2026-34403 being exploited?

CVE-2026-34403 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-34403 affect?

CVE-2026-34403 affects nginx ui. Severity is high (CVSS 8.1). 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

Q: How urgent is CVE-2026-34403?

Priority 40/100. High severity; Public exploit reference; On your watchlist

This month

HIGH 8.1WATCHLISTUPGRADE

CVE-2026-34403 is a high-severity flaw (CVSS 8.1) affecting nginx ui. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 W

Why this priority

High severity
Public exploit reference
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 93%)
CISA exploited list	No
Weakness	CWE-1385
Published	2026-04-20
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: nginxui

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-20 21:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

nginxui nginx ui UPGRADE

Affected: < 2.3.5

Fixed in: 2.3.5

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy nginx-ui || rpm -q nginx-ui || nginx-ui --version

2. UPGRADE to 2.3.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nginx-ui

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nginx-ui

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-34403?

nginx ui: upgrade to 2.3.5. Exact commands for each OS are on this page.

Is CVE-2026-34403 being exploited?

CVE-2026-34403 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-34403 affect?

CVE-2026-34403 affects nginx ui. Severity is high (CVSS 8.1). 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

How urgent is CVE-2026-34403?

Priority 40/100. High severity; Public exploit reference; On your watchlist

Software pages

nginx vulnerabilities

Related CVEs

CVE-2026-33031 HIGH 8.1 UPGRADE Nginx UI is a web user interface for the Nginx web server
CVE-2026-42221 HIGH 8.1 UPGRADE Nginx UI is a web user interface for the Nginx web server
CVE-2026-42222 HIGH 8.1 DOWNGRADE Nginx UI is a web user interface for the Nginx web server
CVE-2026-42220 MEDIUM 6.5 UPGRADE Nginx UI is a web user interface for the Nginx web server
CVE-2026-42223 MEDIUM 6.5 UPGRADE Nginx UI is a web user interface for the Nginx web server

References

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