Fix CVE-2024-48510

src/Zip/ZipEntry.Extract.cs

@@ -1389,6 +1389,16 @@ bool IsDoneWithOutputToBaseDir(string baseDir, out string outFileName)
 
             // workitem 10639
             outFileName = outFileName.Replace('/', Path.DirectorySeparatorChar);
+
+            // Resolve any directory traversal sequence and compare the result with the intended base directory
+            // where the file or folder will be created.
+            // https://gist.github.com/thomas-chauchefoin-bentley-systems/855218959116f870f08857cce2aec731
+            var canonicalOutPath = Path.GetFullPath(outFileName);
+            var canonicalBaseDir = Path.GetFullPath(baseDir);
+            if (!canonicalOutPath.StartsWith(canonicalBaseDir, StringComparison.OrdinalIgnoreCase))
+            {
+                throw new IOException(string.Format("Extracting {0} would write to {1}, outside of {2}; rejecting.", outFileName, canonicalOutPath, canonicalBaseDir));
+            }
 
             // check if it is a directory
             if (IsDirectory || FileName.EndsWith("/"))

test/BasicTest.cs

@@ -1,14 +1,52 @@
 using Xunit;
+using Xunit.Abstractions;
 
-namespace Ionic.Zip.Tests
+namespace Ionic.Zip.Tests;
+
+public class BasicTest
 {
-    public class BasicTest
+    private readonly ITestOutputHelper _output;
+
+    public BasicTest(ITestOutputHelper output)
+    {
+        _output = output;
+    }
+
+    [Fact]
+    public void TestCreate()
+    {
+        var result = new ZipFile();
+        Assert.NotNull(result);
+    }
+
+    [Fact]
+    public void Extract_ZipWithAbsolutePathsOutside()
     {
-        [Fact]
-        public void TestCreate()
+        Assert.Throws<IOException>(() => Extract_ZipFile("absolute-path-traversal.zip"));
+        Assert.False(File.Exists(@"C:\Windows\Temp\foo"));
+    }
+
+    private void Extract_ZipFile(string fileName)
+    {
+        var sourceDir = Directory.GetCurrentDirectory();
+        _output.WriteLine("Current Dir: {0}", sourceDir);
+
+        var fqFileName = Path.Combine(sourceDir, "zips", fileName);
+
+        _output.WriteLine("Reading zip file: '{0}'", fqFileName);
+        using var zip = ZipFile.Read(fqFileName);
+        const string extractDir = "extract";
+        foreach (ZipEntry e in zip)
         {
-            var result = new ZipFile();
-            Assert.NotNull(result);
+            _output.WriteLine("{1,-22} {2,9} {3,5:F0}%   {4,9}  {5,3} {6:X8} {0}",
+                e.FileName,
+                e.LastModified.ToString("yyyy-MM-dd HH:mm:ss"),
+                e.UncompressedSize,
+                e.CompressionRatio,
+                e.CompressedSize,
+                (e.UsesEncryption) ? "Y" : "N",
+                e.Crc);
+            e.Extract(extractDir);
         }
     }
-}
+}

test/ProDotNetZipNetStandardTest.csproj

@@ -26,4 +26,10 @@
 		<ProjectReference Include="..\src\ProDotNetZipNetStandard.csproj" />
 	</ItemGroup>
 
+	<ItemGroup>
+	  <None Update="zips\absolute-path-traversal.zip">
+	    <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+	  </None>
+	</ItemGroup>
+
 </Project>