fix: sanitize archive entry paths before extraction to prevent path traversal

Move path sanitization before directory handling in extractFile so
directory entries with "../" prefixes are rejected the same way file
entries already are. Add the same sanitization to extractSevenZipMultiPart
and both zip extraction loops in the Windows updater, which had no path
validation at all.

cmd/updater/updater_windows.go

@@ -37,15 +37,17 @@ func installByInstaller(killSignalChan chan<- any, packagePath, destDir string)
 	}
 	defer reader.Close()
 
-	// Find the installer file
 	var installerPath string
 	for _, file := range reader.File {
+		cleanName := filepath.Clean(file.Name)
+		if strings.HasPrefix(cleanName, "..") || filepath.IsAbs(cleanName) {
+			continue
+		}
 		if file.FileInfo().IsDir() {
 			continue
 		}
 
-		// Extract file
-		path := filepath.Join(tempDir, file.Name)
+		path := filepath.Join(tempDir, cleanName)
 
 		if err := os.MkdirAll(filepath.Dir(path), os.ModePerm); err != nil {
 			return err
@@ -101,7 +103,11 @@ func installByPortable(killSignalChan chan<- any, packagePath, destDir string) e
 	defer reader.Close()
 
 	for _, file := range reader.File {
-		path := filepath.Join(destDir, file.Name)
+		cleanName := filepath.Clean(file.Name)
+		if strings.HasPrefix(cleanName, "..") || filepath.IsAbs(cleanName) {
+			continue
+		}
+		path := filepath.Join(destDir, cleanName)
 
 		if file.FileInfo().IsDir() {
 			os.MkdirAll(path, file.Mode())

pkg/download/extract.go

@@ -282,19 +282,15 @@ func countArchiveFiles(archivePath string, password string) (int, error) {
 
 // extractFile handles extracting a single file from an archive
 func extractFile(ctx context.Context, fileInfo archives.FileInfo, destDir string) error {
-	// Skip directories, they will be created when extracting files
-	if fileInfo.IsDir() {
-		destPath := filepath.Join(destDir, fileInfo.NameInArchive)
-		return os.MkdirAll(destPath, fileInfo.Mode())
-	}
-
-	// Sanitize the path to prevent path traversal attacks
 	cleanPath := filepath.Clean(fileInfo.NameInArchive)
 	if strings.HasPrefix(cleanPath, "..") || filepath.IsAbs(cleanPath) {
-		// Skip files with suspicious paths
 		return nil
 	}
 
+	if fileInfo.IsDir() {
+		return os.MkdirAll(filepath.Join(destDir, cleanPath), fileInfo.Mode())
+	}
+
 	destPath := filepath.Join(destDir, cleanPath)
 
 	// Create parent directories

pkg/download/extract_7z.go

@@ -4,6 +4,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/bodgit/sevenzip"
 )
@@ -43,7 +44,11 @@ func extractSevenZipMultiPart(firstPartPath string, destDir string, password str
 	// Extract files with progress tracking
 	extractedFiles := 0
 	for _, f := range reader.File {
-		destPath := filepath.Join(destDir, f.Name)
+		cleanName := filepath.Clean(f.Name)
+		if strings.HasPrefix(cleanName, "..") || filepath.IsAbs(cleanName) {
+			continue
+		}
+		destPath := filepath.Join(destDir, cleanName)
 
 		if f.FileInfo().IsDir() {
 			if err := os.MkdirAll(destPath, f.Mode()); err != nil {
@@ -52,7 +57,6 @@ func extractSevenZipMultiPart(firstPartPath string, destDir string, password str
 			continue
 		}
 
-		// Ensure parent directory exists
 		if err := os.MkdirAll(filepath.Dir(destPath), 0755); err != nil {
 			return err
 		}