From 1968cc55a4b97b31ed37493e2d4c01490f90eab1 Mon Sep 17 00:00:00 2001
From: Mouse <mouseparker123@gmail.com>
Date: Fri, 17 Apr 2026 15:08:28 -0700
Subject: [PATCH] feat: harden remote profile loading by validating
 content-type

---
 src/parser/index.ts             | 33 ++++++++++++++++++++++++
 test/parser/loadFromUrl.test.ts | 45 +++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/src/parser/index.ts b/src/parser/index.ts
index 5a1ba36..516c764 100644
--- a/src/parser/index.ts
+++ b/src/parser/index.ts
@@ -32,6 +32,12 @@ import {
  */
 export class YouMdParserImpl implements YouMdParser {
   private readonly maxFileSize: number;
+  private static readonly ALLOWED_REMOTE_CONTENT_TYPES = [
+    "text/markdown",
+    "text/plain",
+    "text/x-markdown",
+    "application/markdown",
+  ];
 
   constructor(options?: { maxFileSize?: number }) {
     this.maxFileSize = options?.maxFileSize ?? MAX_FILE_SIZE;
@@ -350,6 +356,33 @@ export class YouMdParserImpl implements YouMdParser {
         };
       }
 
+      const contentTypeHeader = response.headers.get("content-type");
+      if (contentTypeHeader) {
+        const normalizedContentType = contentTypeHeader
+          .split(";")[0]
+          ?.trim()
+          .toLowerCase();
+
+        if (
+          normalizedContentType &&
+          !YouMdParserImpl.ALLOWED_REMOTE_CONTENT_TYPES.includes(
+            normalizedContentType
+          )
+        ) {
+          return {
+            profile: createEmptyProfile(),
+            success: false,
+            errors: [
+              {
+                code: "NETWORK_ERROR",
+                message: `Unsupported content type: ${normalizedContentType}`,
+              },
+            ],
+            warnings: [],
+          };
+        }
+      }
+
       const maxSize = parseOptions?.maxFileSize ?? this.maxFileSize;
       const contentLengthHeader = response.headers.get("content-length");
       if (contentLengthHeader) {
diff --git a/test/parser/loadFromUrl.test.ts b/test/parser/loadFromUrl.test.ts
index 4a591f9..909c261 100644
--- a/test/parser/loadFromUrl.test.ts
+++ b/test/parser/loadFromUrl.test.ts
@@ -76,4 +76,49 @@ describe("loadFromUrl hardening", () => {
     expect(result.success).toBe(false);
     expect(result.errors.some((e) => e.code === "FILE_TOO_LARGE")).toBe(true);
   });
+
+  it("rejects unsupported content types before reading body", async () => {
+    const parser = createParser();
+    const textSpy = vi.fn(async () => "---\nschema_version: \"1.1\"\n---\n# Me");
+
+    vi.spyOn(globalThis, "fetch").mockResolvedValue({
+      ok: true,
+      status: 200,
+      statusText: "OK",
+      headers: {
+        get: (name: string) =>
+          name.toLowerCase() === "content-type" ? "application/json" : null,
+      },
+      text: textSpy,
+    } as unknown as Response);
+
+    const result = await parser.loadFromUrl("https://example.com/profile.md");
+
+    expect(result.success).toBe(false);
+    expect(result.errors.some((e) => e.code === "NETWORK_ERROR")).toBe(true);
+    expect(result.errors[0]?.message).toContain("Unsupported content type");
+    expect(textSpy).not.toHaveBeenCalled();
+  });
+
+  it("accepts allowed content types with charset parameters", async () => {
+    const parser = createParser();
+
+    vi.spyOn(globalThis, "fetch").mockResolvedValue({
+      ok: true,
+      status: 200,
+      statusText: "OK",
+      headers: {
+        get: (name: string) =>
+          name.toLowerCase() === "content-type"
+            ? "text/markdown; charset=utf-8"
+            : null,
+      },
+      body: null,
+      text: vi.fn(async () => "---\nschema_version: \"1.1\"\n---\n# Me"),
+    } as unknown as Response);
+
+    const result = await parser.loadFromUrl("https://example.com/profile.md");
+
+    expect(result.success).toBe(true);
+  });
 });