Is CVE-2026-34403 actively exploited?

No active exploitation of CVE-2026-34403 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-34403 be exploited remotely?

Yes. CVE-2026-34403 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-34403?

CVE-2026-34403 has a CVSS score of 8.1 (HIGH).

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HIGH

CVE-2026-34403

CWE-1385Published: April 20, 2026· Updated: Apr 22, 2026

8.1

CVSS v3.1

EPSS:0.03%probability of exploitation in 30 daysPercentile:7.3th

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.

NVD Source

Technical Analysis

CVE-2026-34403 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), with a CVSS base score of 8.1.