From d046f5b9b45074a85ea0b021088a3558793ed6da Mon Sep 17 00:00:00 2001
From: MarkXian <mark-xian@foxmail.com>
Date: Tue, 28 Jul 2026 11:24:10 +0800
Subject: [PATCH] fix(kap-server): sanitize download filenames

---
 .changeset/safe-download-filenames.md | 5 +++++
 packages/kap-server/src/routes/fs.ts  | 5 +++--
 packages/kap-server/test/fs.test.ts   | 5 +++++
 3 files changed, 13 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/safe-download-filenames.md

diff --git a/.changeset/safe-download-filenames.md b/.changeset/safe-download-filenames.md
new file mode 100644
index 0000000000..6b8812bf46
--- /dev/null
+++ b/.changeset/safe-download-filenames.md
@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Sanitize filenames in session file download response headers.
diff --git a/packages/kap-server/src/routes/fs.ts b/packages/kap-server/src/routes/fs.ts
index 4a55cd33d4..6e99a816c7 100644
--- a/packages/kap-server/src/routes/fs.ts
+++ b/packages/kap-server/src/routes/fs.ts
@@ -590,8 +590,9 @@ function buildValidationEnvelope(
   };
 }
 
-function sanitizeFilename(rel: string): string {
+export function sanitizeFilename(rel: string): string {
   const segs = rel.split('/');
   const base = segs[segs.length - 1] ?? rel;
-  return base.replace(/"/g, '\\"');
+  const sanitized = base.replace(/[\u0000-\u001f\u007f"\\]/g, '_');
+  return sanitized.length > 0 ? sanitized : 'download';
 }
diff --git a/packages/kap-server/test/fs.test.ts b/packages/kap-server/test/fs.test.ts
index bf1a057cb3..5c61e41bc9 100644
--- a/packages/kap-server/test/fs.test.ts
+++ b/packages/kap-server/test/fs.test.ts
@@ -6,6 +6,7 @@ import { IModelCatalog } from '@moonshot-ai/agent-core-v2';
 import { ErrorCode } from '../src/protocol/error-codes';
 import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 
+import { sanitizeFilename } from '../src/routes/fs';
 import { type RunningServer, startServer } from '../src/start';
 import { authHeaders } from './helpers/auth';
 
@@ -303,4 +304,8 @@ describe('server-v2 /api/v1/sessions/{sid}/fs:*', () => {
     } as never);
     expect(cached.status).toBe(304);
   });
+
+  it('sanitizeFilename strips control characters and path separators', async () => {
+    expect(sanitizeFilename('bad"name\\.txt')).toBe('bad_name_.txt');
+  });
 });