diff --git a/src/main/java/org/zeroturnaround/zip/ZipUtil.java b/src/main/java/org/zeroturnaround/zip/ZipUtil.java
index 7ebc8dd..604866e 100644
--- a/src/main/java/org/zeroturnaround/zip/ZipUtil.java
+++ b/src/main/java/org/zeroturnaround/zip/ZipUtil.java
@@ -1150,6 +1150,15 @@ public void process(InputStream in, ZipEntry zipEntry) throws IOException {
       String name = mapper.map(zipEntry.getName());
       if (name != null) {
         File file = new File(outputDir, name);
+
+        /* If we see the relative traversal string of ".." we need to make sure
+         * that the outputdir + name doesn't leave the outputdir. See
+         * DirectoryTraversalMaliciousTest for details.
+         */
+        if (name.indexOf("..") != -1 && !file.getCanonicalPath().startsWith(outputDir.getCanonicalPath())) {
+          throw new ZipException("The file "+name+" is trying to leave the target output directory of "+outputDir+". Ignoring this file.");
+        }
+
         if (zipEntry.isDirectory()) {
           FileUtils.forceMkdir(file);
         }
@@ -1218,11 +1227,29 @@ public void process(InputStream in, ZipEntry zipEntry) throws IOException {
             parentDirectory = file;
           }
           File destFile = new File(parentDirectory, dirs[dirs.length - 1]);
+
+          /* If we see the relative traversal string of ".." we need to make sure
+           * that the outputdir + name doesn't leave the outputdir. See
+           * DirectoryTraversalMaliciousTest for details.
+           */
+          if (name.indexOf("..") != -1 && !destFile.getCanonicalPath().startsWith(outputDir.getCanonicalPath())) {
+            throw new ZipException("The file "+name+" is trying to leave the target output directory of "+outputDir+". Ignoring this file.");
+          }
+
           FileUtils.copy(in, destFile);
         }
         // it could be that there are just top level files that the unpacker is used for
         else {
           File destFile = new File(outputDir, name);
+
+          /* If we see the relative traversal string of ".." we need to make sure
+           * that the outputdir + name doesn't leave the outputdir. See
+           * DirectoryTraversalMaliciousTest for details.
+           */
+          if (name.indexOf("..") != -1 && !destFile.getCanonicalPath().startsWith(outputDir.getCanonicalPath())) {
+            throw new ZipException("The file "+name+" is trying to leave the target output directory of "+outputDir+". Ignoring this file.");
+          }
+
           FileUtils.copy(in, destFile);
         }
       }
@@ -1258,6 +1285,15 @@ else if (!rootDir.equals(root)) {
       String name = mapper.map(getUnrootedName(root, zipEntry.getName()));
       if (name != null) {
         File file = new File(outputDir, name);
+
+        /* If we see the relative traversal string of ".." we need to make sure
+         * that the outputdir + name doesn't leave the outputdir. See
+         * DirectoryTraversalMaliciousTest for details.
+         */
+        if (name.indexOf("..") != -1 && !file.getCanonicalPath().startsWith(outputDir.getCanonicalPath())) {
+          throw new ZipException("The file "+name+" is trying to leave the target output directory of "+outputDir+". Ignoring this file.");
+        }
+
         if (zipEntry.isDirectory()) {
           FileUtils.forceMkdir(file);
         }
diff --git a/src/test/java/org/zeroturnaround/zip/DirectoryTraversalMaliciousTest.java b/src/test/java/org/zeroturnaround/zip/DirectoryTraversalMaliciousTest.java
new file mode 100644
index 0000000..8eede3d
--- /dev/null
+++ b/src/test/java/org/zeroturnaround/zip/DirectoryTraversalMaliciousTest.java
@@ -0,0 +1,61 @@
+package org.zeroturnaround.zip;
+
+/**
+ *    Copyright (C) 2012 ZeroTurnaround LLC <support@zeroturnaround.com>
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+import java.io.File;
+
+import junit.framework.TestCase;
+
+public class DirectoryTraversalMaliciousTest extends TestCase {
+  /*
+   * This is the contents of the file. There is one evil file that tries to get out of the
+   * target.
+   *
+   * $ unzip -t zip-slip.zip
+   * Archive: zip-slip.zip
+   * testing: good.txt OK
+   * testing: ../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../../tmp/evil.txt OK
+   * No errors detected in compressed data of zip-slip.zip.
+   */
+  private static final File badFile = new File("src/test/resources/zip-malicious-traversal.zip");
+  private static final File badFileBackslashes = new File("src/test/resources/zip-malicious-traversal-backslashes.zip");
+
+  public void testUnpackDoesntLeaveTarget() throws Exception {
+    File file = File.createTempFile("temp", null);
+    File tmpDir = file.getParentFile();
+
+    try {
+      ZipUtil.unpack(badFile, tmpDir);
+      fail();
+    }
+    catch (ZipException e) {
+      assertTrue(true);
+    }
+  }
+
+  public void testUnwrapDoesntLeaveTarget() throws Exception {
+    File file = File.createTempFile("temp", null);
+    File tmpDir = file.getParentFile();
+
+    try {
+      ZipUtil.iterate(badFileBackslashes, new ZipUtil.BackslashUnpacker(tmpDir));
+      fail();
+    }
+    catch (ZipException e) {
+      assertTrue(true);
+    }
+  }
+}
diff --git a/src/test/resources/zip-malicious-traversal-backslashes.zip b/src/test/resources/zip-malicious-traversal-backslashes.zip
new file mode 100644
index 0000000..a67ff8b
Binary files /dev/null and b/src/test/resources/zip-malicious-traversal-backslashes.zip differ
diff --git a/src/test/resources/zip-malicious-traversal.zip b/src/test/resources/zip-malicious-traversal.zip
new file mode 100644
index 0000000..38b3f49
Binary files /dev/null and b/src/test/resources/zip-malicious-traversal.zip differ