Cap JSON parsing depth across protocol inputs

changelog.d/unreleased/3012.security.md

@@ -0,0 +1,16 @@
+---
+category: security
+issues:
+  - 3012
+affected:
+  - src/CodeIndex/Mcp/McpServer.cs
+  - tests/CodeIndex.Tests/McpServerTests.cs
+---
+
+## English
+
+- **MCP response-frame detection now enforces the JSON depth cap (#3012)** — response-frame probing rejects over-depth JSON before classification, matching the guarded MCP request and cancellation parsing paths.
+
+## 日本語
+
+- **MCP response frame 判定で JSON 深さ上限を適用しました (#3012)** — response frame の事前判定でも過深 JSON を分類前に拒否し、MCP request / cancellation の保護済み parse 経路と揃えました。

changelog.d/unreleased/3014.security.md

@@ -0,0 +1,16 @@
+---
+category: security
+issues:
+  - 3014
+affected:
+  - src/CodeIndex/Mcp/HttpMcpTransport.cs
+  - tests/CodeIndex.Tests/HttpMcpTransportTests.cs
+---
+
+## English
+
+- **HTTP MCP JSON-RPC id probing is covered by the JSON depth cap (#3014)** — over-depth HTTP request bodies no longer expose request-id extraction to unbounded JSON parsing work.
+
+## 日本語
+
+- **HTTP MCP の JSON-RPC id 抽出に JSON 深さ上限を適用しました (#3014)** — 過深な HTTP request body によって request id 抽出が無制限の JSON parse 作業を行わないようにしました。

changelog.d/unreleased/3016.security.md

@@ -0,0 +1,16 @@
+---
+category: security
+issues:
+  - 3016
+affected:
+  - src/CodeIndex/Cli/JsonEnvelopeWrapper.cs
+  - tests/CodeIndex.Tests/JsonEnvelopeWrapperTests.cs
+---
+
+## English
+
+- **JSON envelope raw-item parsing now caps JSON depth (#3016)** — `--json-envelope` keeps over-depth raw output lines as strings instead of parsing them without an explicit nesting limit.
+
+## 日本語
+
+- **JSON envelope の raw item parse に JSON 深さ上限を適用しました (#3016)** — `--json-envelope` は過深な raw output 行を、明示的な入れ子上限なしで parse せず従来どおり文字列として保持します。

changelog.d/unreleased/3021.security.md

@@ -0,0 +1,16 @@
+---
+category: security
+issues:
+  - 3021
+affected:
+  - src/CodeIndex/Lsp/LspServer.cs
+  - tests/CodeIndex.Tests/LspServerTests.cs
+---
+
+## English
+
+- **LSP JSON message parsing now enforces a depth cap (#3021)** — deeply nested LSP payloads are rejected as parse errors instead of being parsed without an explicit nesting limit.
+
+## 日本語
+
+- **LSP JSON message parse に深さ上限を適用しました (#3021)** — 過深な LSP payload は、明示的な入れ子上限なしで parse されず parse error として拒否されます。

changelog.d/unreleased/3022.security.md

@@ -0,0 +1,16 @@
+---
+category: security
+issues:
+  - 3022
+affected:
+  - src/CodeIndex/Cli/QueryCommandRunner.cs
+  - tests/CodeIndex.Tests/QueryCommandRunnerTests.cs
+---
+
+## English
+
+- **Batch query JSON input now enforces a depth cap (#3022)** — `cdidx batch` rejects over-depth JSON lines during parsing before command argument processing.
+
+## 日本語
+
+- **batch query の JSON 入力に深さ上限を適用しました (#3022)** — `cdidx batch` は過深な JSON 行を command argument 処理前の parse 段階で拒否します。

changelog.d/unreleased/3036.security.md

@@ -0,0 +1,16 @@
+---
+category: security
+issues:
+  - 3036
+affected:
+  - src/CodeIndex/Cli/ActiveWorkspace.cs
+  - tests/CodeIndex.Tests/WorkspaceCommandRunnerTests.cs
+---
+
+## English
+
+- **Active workspace state parsing now enforces a JSON depth cap (#3036)** — deeply nested `active.json` files are ignored with the existing warning path instead of overriding workspace DB resolution.
+
+## 日本語
+
+- **active workspace state の parse に JSON 深さ上限を適用しました (#3036)** — 過深な `active.json` は既存の warning 経路で無視され、workspace DB 解決を上書きしません。

changelog.d/unreleased/3043.security.md

@@ -0,0 +1,16 @@
+---
+category: security
+issues:
+  - 3043
+affected:
+  - src/CodeIndex/Mcp/McpIndexRunLock.cs
+  - tests/CodeIndex.Tests/McpServerTests.cs
+---
+
+## English
+
+- **MCP index-run lock metadata parsing now enforces a JSON depth cap (#3043)** — deeply nested lock holder metadata is treated as unavailable diagnostics instead of being parsed without an explicit nesting limit.
+
+## 日本語
+
+- **MCP index-run lock metadata の parse に JSON 深さ上限を適用しました (#3043)** — 過深な lock holder metadata は、明示的な入れ子上限なしで parse せず diagnostic 不明として扱います。

src/CodeIndex/Cli/ActiveWorkspace.cs

@@ -9,6 +9,11 @@ internal static class ActiveWorkspace
 {
     internal const string EnvironmentVariable = "CDIDX_ACTIVE_WORKSPACE";
     private const int MaxStateBytes = 64 * 1024;
+    internal const int MaxStateJsonDepth = 16;
+    private static readonly JsonDocumentOptions StateJsonDocumentOptions = new()
+    {
+        MaxDepth = MaxStateJsonDepth,
+    };
 
     internal static string StatePath
     {
@@ -41,7 +46,7 @@ internal static string StatePath
                 return null;
             }
 
-            using var document = JsonDocument.Parse(text);
+            using var document = JsonDocument.Parse(text, StateJsonDocumentOptions);
             var root = document.RootElement;
             var name = ReadString(root, "name") ?? "default";
             var workspaceRoot = ReadString(root, "root") ?? Environment.CurrentDirectory;

src/CodeIndex/Cli/JsonEnvelopeWrapper.cs

@@ -18,6 +18,7 @@ internal static class JsonEnvelopeWrapper
 {
     internal const string EnvelopeFlag = "--json-envelope";
     internal const int MaxCapturedOutputChars = 10 * 1024 * 1024;
+    internal const int MaxRawJsonItemDepth = 32;
 
     private static readonly HashSet<string> WrappableCommands = new(StringComparer.Ordinal)
     {
@@ -210,7 +211,7 @@ private static JsonArray ParseRawJsonItems(string raw)
             JsonNode? node;
             try
             {
-                node = JsonNode.Parse(line);
+                node = JsonNode.Parse(line, documentOptions: new JsonDocumentOptions { MaxDepth = MaxRawJsonItemDepth });
             }
             catch (JsonException)
             {

src/CodeIndex/Cli/QueryCommandRunner.cs

@@ -24,6 +24,7 @@ public static class QueryCommandRunner
     internal const int DefaultImpactLimit = 50;
     internal const int BatchMaxLineChars = 1024 * 1024;
     internal const int BatchMaxArgumentCount = 256;
+    internal const int BatchMaxJsonDepth = 32;
     internal const string DefaultLimitEnvironmentVariable = "CDIDX_DEFAULT_LIMIT";
     internal const string DefaultSnippetLinesEnvironmentVariable = "CDIDX_DEFAULT_SNIPPET_LINES";
     internal const string DefaultMaxLineWidthEnvironmentVariable = "CDIDX_DEFAULT_MAX_LINE_WIDTH";
@@ -33,6 +34,11 @@ public static class QueryCommandRunner
     private const string LanguageCapabilitySymbols = "symbols";
     internal static readonly TimeSpan DefaultStaleAfter = TimeSpan.FromHours(24);
     internal static TimeProvider TimeProvider { get; set; } = TimeProvider.System;
+    private static readonly JsonDocumentOptions BatchJsonDocumentOptions = new()
+    {
+        MaxDepth = BatchMaxJsonDepth,
+    };
+
     [ThreadStatic]
     private static DbReader? s_batchReader;
 
@@ -371,7 +377,7 @@ private static bool TryParseBatchLine(string line, int lineNumber, out string co
 
         try
         {
-            using var document = JsonDocument.Parse(line);
+            using var document = JsonDocument.Parse(line, BatchJsonDocumentOptions);
             if (document.RootElement.ValueKind != JsonValueKind.Array || document.RootElement.GetArrayLength() == 0)
             {
                 Console.Error.WriteLine($"Error: batch line {lineNumber} must be a non-empty JSON string array.");

src/CodeIndex/Lsp/LspServer.cs

@@ -15,6 +15,12 @@ internal sealed class LspServer : IDisposable
     internal const int MaxLspFrameBytes = 8 * 1024 * 1024;
     internal const int MaxLspHeaderLineBytes = 8 * 1024;
     internal const int MaxPositionDocumentBytes = 4 * 1024 * 1024;
+    internal const int MaxJsonDepth = 32;
+    private static readonly JsonDocumentOptions LspJsonDocumentOptions = new()
+    {
+        MaxDepth = MaxJsonDepth,
+    };
+
     private readonly DbReader _reader;
     private readonly string _version;
     private readonly JsonSerializerOptions _jsonOptions;
@@ -54,7 +60,7 @@ public int Run(Stream input, Stream output)
         JsonDocument document;
         try
         {
-            document = JsonDocument.Parse(payload);
+            document = JsonDocument.Parse(payload, LspJsonDocumentOptions);
         }
         catch (JsonException)
         {
@@ -74,7 +80,7 @@ public int Run(Stream input, Stream output)
 
                 var method = root.TryGetProperty("method", out var methodElement) ? methodElement.GetString() : null;
                 hasId = root.TryGetProperty("id", out var idElement);
-                id = hasId ? JsonNode.Parse(idElement.GetRawText()) : null;
+                id = hasId ? JsonNode.Parse(idElement.GetRawText(), documentOptions: LspJsonDocumentOptions) : null;
 
                 if (method == null)
                     return hasId ? Error(id, -32600, "Invalid Request") : null;

src/CodeIndex/Mcp/McpIndexRunLock.cs

@@ -8,7 +8,12 @@ internal sealed class McpIndexRunLock : IDisposable
 {
     internal const string LockFileName = "index.lock";
     private const int MaxInfoBytes = 4 * 1024;
+    internal const int MaxInfoJsonDepth = 16;
     private static readonly TimeSpan StaleInfoGracePeriod = TimeSpan.FromSeconds(2);
+    private static readonly JsonDocumentOptions InfoJsonDocumentOptions = new()
+    {
+        MaxDepth = MaxInfoJsonDepth,
+    };
 
     private readonly FileStream _stream;
     private readonly string _infoPath;
@@ -97,7 +102,7 @@ private static string BuildBusyMessage(string infoPath)
             if (string.IsNullOrWhiteSpace(text))
                 return null;
 
-            using var document = JsonDocument.Parse(text);
+            using var document = JsonDocument.Parse(text, InfoJsonDocumentOptions);
             var root = document.RootElement;
             if (!root.TryGetProperty("pid", out var pidElement) || !pidElement.TryGetInt32(out var pid))
                 return null;

src/CodeIndex/Mcp/McpServer.cs

@@ -833,7 +833,7 @@ private static bool IsServerResponseFrame(string frame)
     {
         try
         {
-            var node = JsonNode.Parse(frame);
+            var node = JsonNode.Parse(frame, documentOptions: new JsonDocumentOptions { MaxDepth = MaxJsonDepth });
             return node is JsonObject obj
                 && obj.ContainsKey("id")
                 && obj["method"] is null

tests/CodeIndex.Tests/HttpMcpTransportTests.cs

@@ -192,6 +192,20 @@ public async Task HttpTransport_RequestLogger_RecordsMethodStatusDurationAndAuth
         Assert.Equal((int)HttpStatusCode.OK, okPost.StatusCode);
     }
 
+    [Fact]
+    public async Task HttpTransport_RequestLogger_TooDeepJsonRpcIdReturnsNull_Issue3014()
+    {
+        var records = new ConcurrentQueue<HttpMcpTransport.HttpRequestLogRecord>();
+        await using var harness = await McpHttpHarness.StartAsync(_dbPath, requestLogger: records.Enqueue);
+
+        using var response = await harness.PostJsonAsync(BuildNestedJsonRpcRequest(McpServer.MaxJsonDepth + 1));
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var snapshot = await WaitForRequestLogRecordsAsync(records, 1);
+        var record = Assert.Single(snapshot, record => record.Method == "POST");
+        Assert.Null(record.RequestId);
+    }
+
     [Fact]
     public async Task HttpTransport_TwoSequentialRequests_ShareWarmServer()
     {
@@ -819,6 +833,14 @@ private static string BuildNestedJsonRpcResponse(int nestedObjectCount)
         return builder.ToString();
     }
 
+    private static string BuildNestedJsonRpcRequest(int nestedObjectCount)
+    {
+        var builder = new StringBuilder("""{"jsonrpc":"2.0","id":1,"method":"ping","params":""");
+        AppendNestedObject(builder, nestedObjectCount);
+        builder.Append('}');
+        return builder.ToString();
+    }
+
     private static void AppendNestedObject(StringBuilder builder, int nestedObjectCount)
     {
         for (var i = 0; i < nestedObjectCount; i++)

tests/CodeIndex.Tests/JsonEnvelopeWrapperTests.cs

@@ -1,3 +1,4 @@
+using System.Text;
 using System.Text.Json;
 using CodeIndex.Cli;
 
@@ -268,6 +269,29 @@ public void RunWrapped_CapturedOutputExceedsLimit_ReturnsJsonErrorEnvelope_Issue
         Assert.Equal(0, document.RootElement.GetProperty("results").GetArrayLength());
     }
 
+    [Fact]
+    public void RunWrapped_TooDeepRawJsonItem_KeepsLineAsString_Issue3016()
+    {
+        var rawLine = BuildNestedRawJson(JsonEnvelopeWrapper.MaxRawJsonItemDepth + 1);
+        var (exitCode, stdout, stderr) = CaptureConsole(() => JsonEnvelopeWrapper.RunWrapped(
+            "search",
+            ["Needle", "--json-envelope"],
+            "1.0.0",
+            _jsonOptions,
+            _ =>
+            {
+                Console.WriteLine(rawLine);
+                return CommandExitCodes.Success;
+            }));
+
+        Assert.Equal(CommandExitCodes.Success, exitCode);
+        Assert.Equal(string.Empty, stderr);
+        using var document = JsonDocument.Parse(stdout);
+        var result = Assert.Single(document.RootElement.GetProperty("results").EnumerateArray());
+        Assert.Equal(JsonValueKind.String, result.ValueKind);
+        Assert.Equal(rawLine, result.GetString());
+    }
+
     [Fact]
     public void Symbols_WithEnvelope_NormalizesQueryFromExtraNames()
     {
@@ -298,4 +322,18 @@ public void Symbols_WithEnvelope_NormalizesQueryFromExtraNames()
 
     private static (int ExitCode, string Stdout, string Stderr) CaptureConsole(Func<int> action)
         => ConsoleCapture.Capture(action);
+
+    private static string BuildNestedRawJson(int nestedObjectCount)
+    {
+        var builder = new StringBuilder("""{"value":""");
+        for (var i = 0; i < nestedObjectCount; i++)
+            builder.Append("""{"next":""");
+
+        builder.Append('0');
+
+        for (var i = 0; i < nestedObjectCount; i++)
+            builder.Append('}');
+        builder.Append('}');
+        return builder.ToString();
+    }
 }

tests/CodeIndex.Tests/LspServerTests.cs

@@ -83,6 +83,28 @@ public void HandleMessage_Initialize_AdvertisesCoreCapabilities()
         }
     }
 
+    [Fact]
+    public void HandleMessage_TooDeepJson_ReturnsParseError_Issue3021()
+    {
+        var projectRoot = TestProjectHelper.CreateTempProject("cdidx_lsp_depth");
+        try
+        {
+            var dbPath = TestProjectHelper.CreateProjectDb(projectRoot);
+            using var db = new DbContext(dbPath);
+            using var server = new LspServer(new DbReader(db), "1.2.3", ProgramRunner.CreateDefaultJsonOptions(), projectRoot);
+
+            var response = server.HandleMessage(BuildNestedLspRequest(LspServer.MaxJsonDepth + 1));
+
+            Assert.NotNull(response);
+            Assert.Equal(-32700, response!["error"]!["code"]!.GetValue<int>());
+            Assert.Null(response["id"]);
+        }
+        finally
+        {
+            TestProjectHelper.DeleteDirectory(projectRoot);
+        }
+    }
+
     [Fact]
     public void Run_MalformedJsonFrame_WritesParseErrorAndContinues()
     {
@@ -667,6 +689,20 @@ private static int CharacterOf(string source, int line, string value)
         return lines[line].IndexOf(value, StringComparison.Ordinal);
     }
 
+    private static string BuildNestedLspRequest(int nestedObjectCount)
+    {
+        var builder = new StringBuilder("""{"jsonrpc":"2.0","id":1,"method":"initialize","params":""");
+        for (var i = 0; i < nestedObjectCount; i++)
+            builder.Append("""{"next":""");
+
+        builder.Append('0');
+
+        for (var i = 0; i < nestedObjectCount; i++)
+            builder.Append('}');
+        builder.Append('}');
+        return builder.ToString();
+    }
+
     private static void MarkGraphReady(string dbPath)
     {
         using var db = new DbContext(dbPath);