From c3105f9a2b7f859847db38a61397394f5a040ac5 Mon Sep 17 00:00:00 2001
From: Andrei-Mihai Minca <48168206+andreiminca@users.noreply.github.com>
Date: Mon, 13 Jul 2026 13:42:25 +0300
Subject: [PATCH] Update path-validation.ts

A path validation bypass vulnerability has been identified on Windows environments within the secure-filesystem-server. The isPathWithinAllowedDirectories function fails to restrict NTFS Alternate Data Streams (ADS). As a result, an attacker can supply paths containing a colon separator (e.g., file.txt:payload.exe), which bypasses directory boundary checks and allows reading or writing hidden data directly to NTFS alternate streams within allowed folders
---
 src/filesystem/path-validation.ts | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/filesystem/path-validation.ts b/src/filesystem/path-validation.ts
index 972e9c49d0..581c17ef9d 100644
--- a/src/filesystem/path-validation.ts
+++ b/src/filesystem/path-validation.ts
@@ -32,6 +32,18 @@ export function isPathWithinAllowedDirectories(absolutePath: string, allowedDire
     return false;
   }
 
+  // Reject Windows Alternate Data Streams (ADS) to prevent path validation bypasses
+  if (process.platform === 'win32' || path.sep === '\\') {
+    const firstColonIndex = normalizedPath.indexOf(':');
+    if (firstColonIndex !== -1) {
+      const hasMoreThanOneColon = normalizedPath.indexOf(':', firstColonIndex + 1) !== -1;
+      const isValidDriveColon = firstColonIndex === 1 && /^[A-Za-z]$/.test(normalizedPath[0]);
+      if (hasMoreThanOneColon || !isValidDriveColon) {
+        return false;
+      }
+    }
+  }
+
   // Verify it's absolute after normalization
   if (!path.isAbsolute(normalizedPath)) {
     throw new Error('Path must be absolute after normalization');