CVE-2026-84320: Nginx UI: Auto backup name allows path traversal outside validated storage path

Vulnerability summary

CVE-2026-84320 is a medium (CVSS 6.3) vulnerability in 0xjacky nginx-ui. EPSS estimates a 0.17% chance of exploitation in the next 30 days, higher than 6% of scored vulnerabilities.

Timeline

1. 12-10-2026
   PublishedVulnerability first disclosed.
2. 13-10-2026
   Last modifiedVulnerability information updated.

Description

Nginx UI is a web user interface for the Nginx web server. Prior to 2.4.3, Nginx UI validates an automatic backup's storage_path, but AutoBackup.GetName returns a user-controlled name without rejecting path separators or parent-directory components, and downstream filename formatting embeds that result in the final archive filename. An authenticated user who can create or modify an automatic backup can cause filepath.Join to resolve the generated archive path outside the validated storage directory, allowing backup archives to be written with the Nginx UI process privileges. For encrypted configuration backups, the adjacent encryption key file can also be written outside the validated directory. This issue is fixed in version 2.4.3.

• CWE-22Improper Limitation of a Pathname to a Restricted DirectoryThe product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.