security: fix path traversal in CLI installer file downloads (#1383)

Fixes path traversal vulnerability where unvalidated filenames from
GitHub API could write files outside intended directory.

Attack vector: MITM attack or DNS hijacking could inject filenames
like "../../../../../../tmp/evil.ts" to write arbitrary files.

Fix: Validate filenames before download - block "..", "/", and "\\"
to ensure files are written only within ${dest}/cli/src/

Severity: HIGH/CRITICAL
Affects: All users running installer via curl|bash

Agent: security-auditor

Co-authored-by: B <6723574+louisgv@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

cli/install.sh

@@ -165,6 +165,16 @@ clone_cli() {
         curl -fsSL "${SPAWN_RAW_BASE}/cli/bun.lock"       -o "${dest}/cli/bun.lock"
         curl -fsSL "${SPAWN_RAW_BASE}/cli/tsconfig.json"  -o "${dest}/cli/tsconfig.json"
         for f in $files; do
+            # SECURITY: Validate filename to prevent path traversal attacks
+            # Block parent directory references (..) and directory separators (/)
+            if [[ "$f" =~ \.\. ]] || [[ "$f" =~ / ]] || [[ "$f" =~ \\ ]]; then
+                log_error "Security: Invalid filename from API (path traversal attempt): $f"
+                log_error "This may indicate a compromised network connection or API response."
+                log_error "Installation aborted for safety."
+                exit 1
+            fi
+
+            # Filename is safe - proceed with download
             curl -fsSL "${SPAWN_RAW_BASE}/cli/src/${f}" -o "${dest}/cli/src/${f}"
         done
     fi

cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@openrouter/spawn",
-  "version": "0.3.1",
+  "version": "0.3.2",
   "type": "module",
   "bin": {
     "spawn": "cli.js"