File Browser vulnerable to command execution allowlist bypass

@@ -6,6 +6,7 @@ import (
 	"log"
 	"net/http"
 	"os/exec"
+	"slices"
 	"strings"
 	"time"
 
@@ -60,15 +61,24 @@ var commandsHandler = withUser(func(w http.ResponseWriter, r *http.Request, d *d
 		}
 	}
 
-	command, err := runner.ParseCommand(d.settings, raw)
+	// Fail fast
+	if !d.server.EnableExec || !d.user.Perm.Execute {
+		if err := conn.WriteMessage(websocket.TextMessage, cmdNotAllowed); err != nil { //nolint:govet
+			wsErr(conn, r, http.StatusInternalServerError, err)
+		}
+
+		return 0, nil
+	}
+
+	command, name, err := runner.ParseCommand(d.settings, raw)
 	if err != nil {
 		if err := conn.WriteMessage(websocket.TextMessage, []byte(err.Error())); err != nil { //nolint:govet
 			wsErr(conn, r, http.StatusInternalServerError, err)
 		}
 		return 0, nil
 	}
 
-	if !d.server.EnableExec || !d.user.CanExecute(command[0]) {
+	if !slices.Contains(d.user.Commands, name) {
 		if err := conn.WriteMessage(websocket.TextMessage, cmdNotAllowed); err != nil { //nolint:govet
 			wsErr(conn, r, http.StatusInternalServerError, err)
 		}

@@ -1,33 +1,24 @@
 package runner
 
 import (
-	"os/exec"
-
 	"github.com/filebrowser/filebrowser/v2/settings"
 )
 
 // ParseCommand parses the command taking in account if the current
 // instance uses a shell to run the commands or just calls the binary
 // directly.
-func ParseCommand(s *settings.Settings, raw string) ([]string, error) {
-	var command []string
+func ParseCommand(s *settings.Settings, raw string) (command []string, name string, err error) {
+	name, args, err := SplitCommandAndArgs(raw)
+	if err != nil {
+		return
+	}
 
 	if len(s.Shell) == 0 || s.Shell[0] == "" {
-		cmd, args, err := SplitCommandAndArgs(raw)
-		if err != nil {
-			return nil, err
-		}
-
-		_, err = exec.LookPath(cmd)
-		if err != nil {
-			return nil, err
-		}
-
-		command = append(command, cmd)
+		command = append(command, name)
 		command = append(command, args...)
 	} else {
-		command = append(s.Shell, raw) //nolint:gocritic
+		command = append(s.Shell, raw)
 	}
 
-	return command, nil
+	return command, name, nil
 }

@@ -60,7 +60,7 @@ func (r *Runner) exec(raw, evt, path, dst string, user *users.User) error {
 		raw = strings.TrimSpace(strings.TrimSuffix(raw, "&"))
 	}
 
-	command, err := ParseCommand(r.Settings, raw)
+	command, _, err := ParseCommand(r.Settings, raw)
 	if err != nil {
 		return err
 	}

@@ -2,7 +2,6 @@ package users
 
 import (
 	"path/filepath"
-	"slices"
 
 	"github.com/spf13/afero"
 
@@ -104,12 +103,3 @@ func (u *User) Clean(baseScope string, fields ...string) error {
 func (u *User) FullPath(path string) string {
 	return afero.FullBaseFsPath(u.Fs.(*afero.BasePathFs), path)
 }
-
-// CanExecute checks if an user can execute a specific command.
-func (u *User) CanExecute(command string) bool {
-	if !u.Perm.Execute {
-		return false
-	}
-
-	return slices.Contains(u.Commands, command)
-}