fix(dotnet): reject invalid UTF-8 metadata version strings (#9156)

* test(process): align symlink fixture with filesystem checkpoints

* test(frida): assert the CLI spawn Evidence contract

* test(mcp): use an unsupported analysis-view parent

* test(browser): separate source-location line bounds from parity

* fix(dotnet): reject invalid UTF-8 metadata version strings

* test(dotnet): preserve valid multibyte metadata version text

src/dotnet/ManagedMetadataHeaps.test.ts

@@ -39,6 +39,24 @@ describe("managed metadata heaps", () => {
     const layout = readManagedMetadataLayout(bytes, 0, bytes.length);
     expect(layout.streamNames).toEqual(["#GUID", "#Strings", "#~"]);
     expect(layout.blob).toBeNull();
+    expect(layout.version).toBe("v4.0.30319");
+
+    bytes.fill(0, 16, 16 + version.length);
+    Buffer.from("v😀é", "utf8").copy(bytes, 16);
+    expect(readManagedMetadataLayout(bytes, 0, bytes.length).version).toBe(
+      "v😀é",
+    );
+
+    bytes[16] = 0xff;
+    expect(() => readManagedMetadataLayout(bytes, 0, bytes.length)).toThrow(
+      expect.objectContaining({
+        issue: expect.objectContaining({
+          code: "invalid-metadata-root",
+          scope: "metadata.version",
+          offset: 16,
+        }),
+      }),
+    );
   });
 
   it("accepts the empty blob entry when an empty #Blob stream is omitted", () => {

src/dotnet/ManagedMetadataLayout.ts

@@ -1,3 +1,5 @@
+import { isUtf8 } from "node:buffer";
+
 import {
   attachManagedDecodeBudget,
   ManagedDecodeBudget,
@@ -241,9 +243,15 @@ const readMetadataStreams = (
   const zero = versionBytes.indexOf(0);
   const decodedVersionLength = zero < 0 ? versionBytes.length : zero;
   budget.reserveString(decodedVersionLength, rootOffset + 16);
-  const version = versionBytes
-    .subarray(0, decodedVersionLength)
-    .toString("utf8");
+  const versionText = versionBytes.subarray(0, decodedVersionLength);
+  if (!isUtf8(versionText))
+    throw managedFailure(
+      "invalid-metadata-root",
+      "metadata.version",
+      "Metadata version is not valid UTF-8",
+      rootOffset + 16,
+    );
+  const version = versionText.toString("utf8");
   let cursor = align4(16 + versionLength);
   requireRange(bytes, rootOffset, cursor, 4, "metadata.stream-count");
   const streamCount = bytes.readUInt16LE(cursor + 2);