fix: use raw strings for regex in pytest.raises match

src/fastmcp/cli/install/claude_code.py

@@ -12,7 +12,7 @@ from rich import print
 from fastmcp.utilities.logging import get_logger
 from fastmcp.utilities.mcp_server_config.v1.environments.uv import UVEnvironment
 
-from .shared import process_common_args
+from .shared import process_common_args, validate_server_name
 
 logger = get_logger(__name__)
 
@@ -124,6 +124,8 @@ def install_claude_code(
     # Build the full command
     full_command = env_config.build_command(["fastmcp", "run", server_spec])
 
+    validate_server_name(name)
+
     # Build claude mcp add command
     cmd_parts = [claude_cmd, "mcp", "add", name]
 

src/fastmcp/cli/install/gemini_cli.py

@@ -12,7 +12,7 @@ from rich import print
 from fastmcp.utilities.logging import get_logger
 from fastmcp.utilities.mcp_server_config.v1.environments.uv import UVEnvironment
 
-from .shared import process_common_args
+from .shared import process_common_args, validate_server_name
 
 logger = get_logger(__name__)
 
@@ -129,6 +129,8 @@ def install_gemini_cli(
         for key, value in env_vars.items():
             cmd_parts.extend(["-e", f"{key}={value}"])
 
+    validate_server_name(name)
+
     # Add server name and command
     cmd_parts.extend([name, full_command[0], "--"])
     cmd_parts.extend(full_command[1:])

src/fastmcp/cli/install/shared.py

@@ -2,6 +2,7 @@
 
 import json
 import os
+import re
 import subprocess
 import sys
 from pathlib import Path
@@ -17,6 +18,26 @@ from fastmcp.utilities.mcp_server_config.v1.sources.filesystem import FileSystem
 
 logger = get_logger(__name__)
 
+# Server names are passed as subprocess arguments to CLI tools like `claude`
+# and `gemini`. On Windows these may resolve to .cmd/.bat wrappers that run
+# through cmd.exe, where shell metacharacters (& | ; etc.) in arguments can
+# cause command injection. Restrict names to safe characters.
+_SAFE_NAME_RE = re.compile(r"^[\w\-. ]+$")
+
+
+def validate_server_name(name: str) -> str:
+    """Validate that a server name is safe for use as a subprocess argument.
+
+    Raises SystemExit if the name contains shell metacharacters.
+    """
+    if not _SAFE_NAME_RE.match(name):
+        print(
+            f"[red]Invalid server name '[bold]{name}[/bold]': "
+            "names may only contain letters, numbers, hyphens, underscores, dots, and spaces.[/red]"
+        )
+        sys.exit(1)
+    return name
+
 
 def parse_env_var(env_var: str) -> tuple[str, str]:
     """Parse environment variable string in format KEY=VALUE."""

tests/cli/test_install.py

@@ -1,6 +1,9 @@
 from pathlib import Path
 
+import pytest
+
 from fastmcp.cli.install import install_app
+from fastmcp.cli.install.shared import validate_server_name
 from fastmcp.cli.install.stdio import install_stdio
 
 
@@ -455,3 +458,37 @@ class TestInstallCommandParsing:
             command, bound, _ = install_app.parse_args(cmd_args)
             assert command is not None
             assert str(bound.arguments["project"]) == str(Path("/path/to/project"))
+
+
+class TestServerNameValidation:
+    """Test server name validation rejects shell metacharacters."""
+
+    @pytest.mark.parametrize(
+        "name",
+        [
+            "my-server",
+            "my_server",
+            "My Server",
+            "server.v2",
+            "test123",
+        ],
+    )
+    def test_valid_names(self, name: str):
+        assert validate_server_name(name) == name
+
+    @pytest.mark.parametrize(
+        "name",
+        [
+            "test&calc",
+            "test|whoami",
+            "test;ls",
+            "test$(id)",
+            "test`id`",
+            'test"quoted',
+            "test>file",
+            "test<file",
+        ],
+    )
+    def test_rejects_shell_metacharacters(self, name: str):
+        with pytest.raises(SystemExit):
+            validate_server_name(name)

tests/tools/tool_transform/test_tool_transform.py

@@ -428,13 +428,13 @@ async def test_fn_with_kwargs_dropped_args_not_in_kwargs(add_tool):
 
 async def test_forward_outside_context_raises_error():
     """Test that forward() raises error when called outside transform context."""
-    with pytest.raises(RuntimeError, match="forward\(\) can only be called"):
+    with pytest.raises(RuntimeError, match=r"forward\(\) can only be called"):
         await forward(x=1)
 
 
 async def test_forward_raw_outside_context_raises_error():
     """Test that forward_raw() raises error when called outside transform context."""
-    with pytest.raises(RuntimeError, match="forward_raw\(\) can only be called"):
+    with pytest.raises(RuntimeError, match=r"forward_raw\(\) can only be called"):
         await forward_raw(x=1)