CVE-2026-42238: Unauthenticated Remote Code Execution via Backup Restore in nginx-ui

Vulnerability summary

CVE-2026-42238 is a critical (CVSS 9.8) Improper Control of Generation of Code vulnerability in 0xjacky nginx-ui. EPSS estimates a 0.97% chance of exploitation in the next 30 days, higher than 61.9% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 04-05-2026
   PublishedVulnerability first disclosed.
2. 05-05-2026
   Last modifiedVulnerability information updated.

Description

Nginx UI is a web user interface for the Nginx web server. Prior to version 2.3.8, nginx-ui exposes a backup restore endpoint (POST /api/restore) that is completely unauthenticated during the first 10 minutes after process startup on any fresh installation. An unauthenticated remote attacker can upload a crafted backup archive that overwrites the application's configuration file (app.ini) and SQLite database. Because the attacker controls the restored app.ini, they can inject an arbitrary OS command into the TestConfigCmd setting. After the application automatically restarts to apply the restored config, a single follow-up request triggers that command as the user running nginx-ui — typically root in Docker deployments. This issue has been patched in version 2.3.8.

• CWE-94Improper Control of Generation of CodeThe product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.