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

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.9% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-06-12 · updated 2026-10-25
Weakness: CWE-22

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.

Affected products

nezhahq nezha: before 2.0.13

References

https://github.com/nezhahq/nezha/security/advisories/GHSA-5c25-7vpj-9mqh

Get alerted when CVE-2026-53519 or the next vulnerability affects your stack