projectdiscovery/nuclei · error

invalid host or port

Error message

invalid host or port

What it means

Returned by mssql.FingerprintMssql when host is an empty string or port is <= 0. It is a pure input-validation failure raised before any network activity; everything else in the function (host allowlist check, dialer lookup, TDS probe) happens after this guard.

Source

Thrown at pkg/js/libs/mssql/fingerprint.go:107

// const mssql = require('nuclei/mssql');
// const info = mssql.FingerprintMssql('acme.com', 1433);
// log(to_json(info));
// ```
func (c *MSSQLClient) FingerprintMssql(ctx context.Context, host string, port int) (MSSQLInfo, error) {
	executionId := ctx.Value("executionId").(string)
	return memoizedfingerprintMssql(ctx, executionId, host, port)
}

// @memo
func fingerprintMssql(ctx context.Context, executionId string, host string, port int) (MSSQLInfo, error) {
	info := MSSQLInfo{
		Host:      host,
		Port:      port,
		Protocol:  "mssql",
		Transport: "tcp",
	}
	if host == "" || port <= 0 {
		return info, fmt.Errorf("invalid host or port")
	}
	if !protocolstate.IsHostAllowed(executionId, host) {
		return info, protocolstate.ErrHostDenied.Msgf(host)
	}
	dialer := protocolstate.GetDialersWithId(executionId)
	if dialer == nil {
		return info, fmt.Errorf("dialers not initialized for %s", executionId)
	}

	conn, err := dialer.Fastdialer.Dial(ctx, "tcp", net.JoinHostPort(host, fmt.Sprintf("%d", port)))
	if err != nil {
		return info, err
	}
	defer func() {
		_ = conn.Close()
	}()

	_ = conn.SetDeadline(time.Now().Add(mssqlFingerprintTimeout))

View on GitHub (pinned to 265b3a3dec)

Solutions

1. Guard the call site: only fingerprint when host is non-empty and port is a positive integer
2. Apply a sensible default port (1433) when the target is known to be MSSQL
3. Parse host:port with split(':') and validate both halves before calling

Example fix

// before
mssql.FingerprintMssql(target, to_number(port)); // port empty -> 0 -> error

// after
if (target && to_number(port) > 0) {
  mssql.FingerprintMssql(target, to_number(port));
}

const p = to_number(port || 1433);
if (!host || !(p > 0)) {
  throw new Error('mssql fingerprint needs a non-empty host and positive port');
}
const info = mssql.FingerprintMssql(String(host), p);

const validHostPort = (h, p) => typeof h === 'string' && h !== '' && Number.isInteger(p) && p > 0;

When it happens

Trigger: mssql.FingerprintMssql('', 1433); mssql.FingerprintMssql('acme.com', 0) — typically because the template derived the port from a variable/extractor that was empty and defaulted to 0, or parsed a host:port string and got an empty host.

Common situations: Templates that fingerprint 'on discovery' where the port is optional and frequently missing; passing a URL where the code expected a bare hostname; JS number coercion yielding NaN/0 for a non-numeric port string.

Related errors

• invalid host or port
• not a mssql service
• invalid goexec method arguments: %w
• parse target: %w
• grpc target host cannot be empty

AI-assisted analysis of projectdiscovery/nuclei@265b3a3dec (2026-08-15). Data as JSON: /api/errors/24c87bac08f56660. Report an issue: GitHub.