fix: validate bracketed IPv6 runtime hosts

Author: xianjianlf2

go/client.go

@@ -36,6 +36,7 @@ import (
 	"fmt"
 	"log"
 	"net"
+	"net/netip"
 	"os"
 	"os/exec"
 	"regexp"
@@ -386,6 +387,10 @@ func parseCLIURL(url string) (string, int) {
 		if err != nil {
 			panic(fmt.Sprintf("Invalid port in URIConnection: %s", url))
 		}
+		addr, err := netip.ParseAddr(host)
+		if err != nil || !addr.Is6() {
+			panic(fmt.Sprintf("Invalid URIConnection format: %s", url))
+		}
 		port, err := strconv.Atoi(portStr)
 		if err != nil || port <= 0 || port > 65535 {
 			panic(fmt.Sprintf("Invalid port in URIConnection: %s", url))

go/client_test.go

@@ -76,6 +76,15 @@ func TestClient_URLParsing(t *testing.T) {
 		}
 	})
 
+	t.Run("should panic for bracketed non-IPv6 host", func(t *testing.T) {
+		defer func() {
+			if r := recover(); r == nil {
+				t.Error("Expected panic for invalid bracketed host")
+			}
+		}()
+		NewClient(&ClientOptions{Connection: URIConnection{URL: "[not-ipv6]:1234"}})
+	})
+
 	t.Run("should parse https://host:port URL format", func(t *testing.T) {
 		client := NewClient(&ClientOptions{
 			Connection: URIConnection{URL: "https://example.com:443"},

nodejs/src/client.ts

@@ -15,7 +15,7 @@ import { spawn, type ChildProcess } from "node:child_process";
 import { randomUUID } from "node:crypto";
 import { existsSync } from "node:fs";
 import { createRequire } from "node:module";
-import { Socket } from "node:net";
+import { isIPv6, Socket } from "node:net";
 import { dirname, join } from "node:path";
 import { fileURLToPath } from "node:url";
 import {
@@ -780,11 +780,16 @@ export class CopilotClient {
         // the existing parser behavior for other inputs.
         const ipv6Match = cleanUrl.match(/^\[([^\]]+)\]:(\d+)$/);
         if (ipv6Match) {
+            const host = ipv6Match[1];
+            if (!isIPv6(host)) {
+                throw new Error(`Invalid cliUrl format: ${url}`);
+            }
+
             const port = parseInt(ipv6Match[2], 10);
             if (isNaN(port) || port <= 0 || port > 65535) {
                 throw new Error(`Invalid port in cliUrl: ${url}`);
             }
-            return { host: ipv6Match[1], port };
+            return { host, port };
         }
 
         // Parse host:port format

nodejs/test/client.test.ts

@@ -2199,6 +2199,15 @@ describe("CopilotClient", () => {
             expect((client as any).isExternalServer).toBe(true);
         });
 
+        it("should reject a bracketed non-IPv6 host", () => {
+            expect(() => {
+                new CopilotClient({
+                    connection: RuntimeConnection.forUri("[not-ipv6]:1234"),
+                    logLevel: "error",
+                });
+            }).toThrow(/Invalid cliUrl format/);
+        });
+
         it("should parse https://host:port URL format", () => {
             const client = new CopilotClient({
                 connection: RuntimeConnection.forUri("https://example.com:443"),

python/copilot/client.py

@@ -15,6 +15,7 @@
 from __future__ import annotations
 
 import asyncio
+import ipaddress
 import inspect
 import logging
 import os
@@ -1655,6 +1656,10 @@ def _parse_cli_url(self, url: str) -> tuple[str, int]:
         if ipv6_match:
             host = ipv6_match.group(1)
             port_text = ipv6_match.group(2)
+            try:
+                ipaddress.IPv6Address(host)
+            except ValueError as e:
+                raise ValueError(f"Invalid cli_url format: {url}") from e
         else:
             # Parse host:port format
             parts = clean_url.split(":")

python/test_client.py

@@ -1214,6 +1214,10 @@ def test_parse_http_ipv6_url(self):
         assert client._actual_host == "::1"
         assert client._is_external_server
 
+    def test_reject_bracketed_non_ipv6_host(self):
+        with pytest.raises(ValueError, match="Invalid cli_url format"):
+            CopilotClient(connection=RuntimeConnection.for_uri("[not-ipv6]:1234"))
+
     def test_parse_https_url(self):
         client = CopilotClient(connection=RuntimeConnection.for_uri("https://example.com:443"))
         assert client._runtime_port == 443