Executive brief
Nezha Monitoring, a server monitoring dashboard, contains a vulnerability where a standard user can hijack the dashboard's own web address. By creating a malicious network configuration (NAT profile) that matches the dashboard's URL, an attacker can block all other users from accessing the management interface or potentially intercept their traffic. This can lead to a complete service outage for the monitoring platform and unauthorized access to data sent to the dashboard.
Technical details
A vulnerability in Nezha Monitoring's NAT management API allows authenticated users to create or update NAT profiles with a 'domain' field that matches the dashboard's own HTTP Host. The dashboard's top-level HTTP/gRPC multiplexer prioritizes NAT configuration lookups via `NATShared.GetNATConfigByDomain(r.Host)` before dispatching to standard dashboard handlers. If an attacker claims the dashboard's Host, they can cause a Denial of Service (if the NAT profile is disabled) or hijack the IO stream via `ServeNAT` (if enabled), forwarding serialized HTTP requests and headers to an attacker-controlled agent. The issue stems from a lack of reserved-host validation in `cmd/dashboard/controller/nat.go`. A fix is available in version 2.1.0.
Affected products
- nezhahq Nezha Monitoring >= 2.0.14, < 2.1.0
Timeline
- 2026-05-31: advisory: GitHub Advisory published
- 2026-06-26: disclosed: CVE-2026-53520 assigned
- 2026-05-31: patched: Fixed in version 2.1.0