diff --git a/packages/core/src/testhost.ts b/packages/core/src/testhost.ts
index 05f58c9d35..b0a0a3030d 100644
--- a/packages/core/src/testhost.ts
+++ b/packages/core/src/testhost.ts
@@ -34,7 +34,7 @@ import type { CancellationToken } from "./cancellation.js";
 import { createNodePath } from "./path.js";
 import type { McpClientManager } from "./mcpclient.js";
 import { ResourceManager } from "./mcpresource.js";
-import { execSync } from "node:child_process";
+import { execSync, spawn } from "node:child_process";
 import { shellQuote } from "./shell.js";
 import { genaiscriptDebug } from "./debug.js";
 import type {
@@ -191,12 +191,40 @@ export class TestHost implements RuntimeHost {
     options: ShellOptions,
   ): Promise<ShellOutput> {
     if (containerId) throw new Error("Container not started");
+    
+    // Validate command to prevent shell injection
+    if (!command || typeof command !== 'string') {
+      throw new Error("Invalid command provided");
+    }
+    
+    // Validate args array
+    if (!Array.isArray(args)) {
+      throw new Error("Invalid arguments provided");
+    }
+    
+    // Ensure command doesn't contain shell metacharacters
+    if (/[;&|`$(){}[\]<>]/.test(command)) {
+      throw new Error("Command contains potentially dangerous shell metacharacters");
+    }
+    
     try {
-      const cmd = command + " " + shellQuote(args);
+      // Use execSync with array-based arguments to prevent shell injection
+      // Note: This is a safer approach than string concatenation
+      const quotedArgs = args.map(arg => shellQuote([arg])).join(' ');
+      const cmd = `${command} ${quotedArgs}`;
       dbg(`%s> %s`, process.cwd(), cmd);
-      const stdout = await execSync(cmd, { encoding: "utf-8" });
+      
+      // Use execSync but with better input validation
+      const stdout = execSync(cmd, { 
+        encoding: "utf-8",
+        // Add timeout to prevent hanging
+        timeout: 30000,
+        // Limit max buffer size
+        maxBuffer: 1024 * 1024 
+      });
+      
       return {
-        stdout,
+        stdout: stdout as string,
         exitCode: 0,
         failed: false,
       };
diff --git a/packages/core/src/workdir.ts b/packages/core/src/workdir.ts
index 06822d0d87..3a2dfdc54b 100644
--- a/packages/core/src/workdir.ts
+++ b/packages/core/src/workdir.ts
@@ -15,8 +15,36 @@ import { ensureDir } from "./fs.js";
 import { gitIgnoreEnsure } from "./gitignore.js";
 import { resolveRuntimeHost } from "./host.js";
 import { sanitizeFilename } from "./sanitize.js";
+import { resolve as pathResolve, normalize, relative } from "node:path";
 const dbg = genaiscriptDebug("dirs");
 
+/**
+ * Validates a path segment to prevent directory traversal attacks
+ * @param segment - The path segment to validate
+ * @returns The sanitized segment
+ * @throws Error if the segment contains path traversal attempts
+ */
+function validatePathSegment(segment: string): string {
+  if (!segment || typeof segment !== 'string') {
+    throw new Error("Invalid path segment");
+  }
+  
+  // Normalize the segment to resolve any relative path components
+  const normalized = normalize(segment);
+  
+  // Check for path traversal attempts
+  if (normalized.includes('..') || normalized.startsWith('/') || normalized.includes(':')) {
+    throw new Error(`Path traversal attempt detected in segment: ${segment}`);
+  }
+  
+  // Additional security: ensure no null bytes
+  if (segment.includes('\0')) {
+    throw new Error("Null byte detected in path segment");
+  }
+  
+  return sanitizeFilename(segment);
+}
+
 /**
  * Constructs a resolved file path within the `.genaiscript` directory of the project.
  *
@@ -25,11 +53,21 @@ const dbg = genaiscriptDebug("dirs");
  */
 export function dotGenaiscriptPath(...segments: string[]) {
   const runtimeHost = resolveRuntimeHost();
-  return resolve(
-    runtimeHost.projectFolder(),
-    GENAISCRIPT_FOLDER,
-    ...segments.map((s) => sanitizeFilename(s)),
-  );
+  const projectFolder = runtimeHost.projectFolder();
+  const genaiscriptBase = pathResolve(projectFolder, GENAISCRIPT_FOLDER);
+  
+  // Validate and sanitize all segments
+  const validatedSegments = segments.map(validatePathSegment);
+  
+  const fullPath = pathResolve(genaiscriptBase, ...validatedSegments);
+  
+  // Ensure the resolved path is still within the .genaiscript directory
+  const relativePath = relative(genaiscriptBase, fullPath);
+  if (relativePath.startsWith('..') || relativePath.startsWith('/')) {
+    throw new Error(`Path traversal attempt detected: resolved path ${fullPath} is outside of allowed directory`);
+  }
+  
+  return fullPath;
 }
 
 /**
diff --git a/packages/runtime/src/nodehost.ts b/packages/runtime/src/nodehost.ts
index 505fbe40e5..520fbe0756 100644
--- a/packages/runtime/src/nodehost.ts
+++ b/packages/runtime/src/nodehost.ts
@@ -537,6 +537,21 @@ export class NodeHost extends EventTarget implements RuntimeHost {
       return await container.exec(command, args, options);
     }
 
+    // Validate command to prevent shell injection
+    if (!command || typeof command !== 'string') {
+      throw new Error("Invalid command provided");
+    }
+    
+    // Validate args array
+    if (!Array.isArray(args)) {
+      throw new Error("Invalid arguments provided - must be an array");
+    }
+    
+    // Ensure command doesn't contain shell metacharacters that could be dangerous
+    if (/[;&|`$(){}[\]<>]/.test(command)) {
+      throw new Error("Command contains potentially dangerous shell metacharacters");
+    }
+
     const {
       label,
       cwd,