crowdsecurity/crowdsec · error

ErrNucleiRunFail

ErrNucleiRunFail

Error message

nuclei run failed

What it means

This sentinel error is returned by NucleiConfig.RunNucleiTemplate/RunWithNucleiTemplate when the spawned `nuclei` command exits with a non-zero status. It wraps the underlying command error (fmt.Errorf with %w), so callers can test with errors.Is(err, ErrNucleiRunFail) to distinguish a nuclei execution failure from config or template-load problems.

Source

Thrown at pkg/hubtest/nucleirunner.go:23

	"context"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"time"

	log "github.com/sirupsen/logrus"
)

type NucleiConfig struct {
	Path           string   `yaml:"nuclei_path"`
	OutputDir      string   `yaml:"output_dir"`
	CmdLineOptions []string `yaml:"cmdline_options"`
}

var (
	ErrNucleiTemplateFail = errors.New("nuclei template failed")
	ErrNucleiRunFail = errors.New("nuclei run failed")
)

func (nc *NucleiConfig) RunNucleiTemplate(ctx context.Context, testName string, templatePath string, target string) error {
	tstamp := time.Now().Unix()

	outputPrefix := fmt.Sprintf("%s/%s-%d", nc.OutputDir, testName, tstamp)
	// CVE-2023-34362_CVE-2023-34362-1702562399_stderr.txt
	args := []string{
		// removing the banner with --silent also removes useful [WRN] lines, so it is what it is
		// "-silent",
		"-u", target,
		"-t", templatePath,
		"-o", outputPrefix + ".json",
	}
	args = append(args, nc.CmdLineOptions...)
	cmd := exec.CommandContext(ctx, nc.Path, args...)

	log.Debugf("Running Nuclei command: '%s'", cmd.String())

View on GitHub (pinned to 909b515798)

Solutions

1. Run the nuclei command manually with the same template and target printed by hubtest to see the real stderr wrapped in this error
2. Verify the template file exists and is valid YAML compatible with your nuclei version (nuclei -t <template> -target <host>)
3. Check that the hubtest item's cmd line_options entries are valid nuclei flags
4. Confirm the nuclei binary is installed, on PATH, and a version compatible with the template
5. Re-run with a reachable target host (NucleiTargetHost) to rule out network/timeout issues

Example fix

// before: opaque failure at the call site
err = nucleiConfig.RunNucleiTemplate(ctx, t.Name, nucleiTemplate, t.NucleiTargetHost)
// after: inspect the wrapped cause
if err != nil {
    if errors.Is(err, ErrNucleiRunFail) {
        log.Fatalf("nuclei execution failed: %v", err) // %v prints the underlying cmd error
    }
    return err
}

// pre-check before running
if _, err := exec.LookPath("nuclei"); err != nil { return fmt.Errorf("nuclei not installed: %w", err) }
if _, err := os.Stat(templatePath); err != nil { return fmt.Errorf("template missing: %w", err) }

func isNucleiRunFail(err error) bool { return errors.Is(err, ErrNucleiRunFail) }

if err := nucleiConfig.RunNucleiTemplate(ctx, name, tpl, target); err != nil {
    if errors.Is(err, ErrNucleiRunFail) {
        log.Printf("nuclei failed: %v", err) // wrapped cmdErr follows the sentinel
    }
    return err
}

When it happens

Trigger: Calling RunNucleiTemplate (e.g. from hubtest's RunWithLogFile via hubtest_item.go:414) when the external nuclei binary returns a non-zero exit code: malformed cmdline_options, unreachable target host, invalid/unsupported template file, or missing/broken nuclei installation.

Common situations: Running crowdsec hubtest against a scenario whose nuclei template is stale or incompatible with the installed nuclei version; CI runners without network access to the target; typos in template path or YAML cmdline_options entries.

Understand the failure class

Background: 'Something went wrong' / 'Request failed (500)' / 'HTTP error! status: 404' — what failed HTTP requests actually mean and how to find the real cause — this error's family across 28 libraries.

Related errors

• ErrNucleiTemplateFail
• can't find crowdsec binary: %w
• can't find cscli binary: %w
• test '%s' doesn't exist in '%s', exiting
• log file '%s' is empty, please fill it with log

AI-assisted analysis of crowdsecurity/crowdsec@909b515798 (2026-09-06). Data as JSON: /api/errors/d57e922bac486530. Report an issue: GitHub.