CVE-2026-53519: Nezha Monitoring: Pre-auth path traversal via /dashboard.. prefix confusion leaks jwt_secret_key

Vulnerability summary

CVE-2026-53519 is a critical (CVSS 9.1) Path Traversal vulnerability in nezhahq nezha. EPSS estimates a 2.29% chance of exploitation in the next 30 days, higher than 83% of scored vulnerabilities.

Timeline

1. 12-06-2026
   PublishedVulnerability first disclosed.
2. 15-06-2026
   Last modifiedVulnerability information updated.

Description

Nezha Monitoring is a self-hostable, lightweight, servers and websites monitoring and O&M tool. Prior to version 2.0.13, fallbackToFrontend in the dashboard's NoRoute handler treats any URL whose raw string starts with /dashboard as an admin-frontend asset request. The check uses strings.HasPrefix, not a path-segment match, so the input /dashboard../data/config.yaml is accepted; strings.TrimPrefix leaves ../data/config.yaml; and path.Join("admin-dist", "../data/config.yaml") normalizes to data/config.yaml — which os.Stat finds and http.ServeFile returns. No authentication required. This issue has been patched in version 2.0.13.

• CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')The 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.