diff --git a/.jules/sentinel.md b/.jules/sentinel.md
new file mode 100644
index 0000000..1e42050
--- /dev/null
+++ b/.jules/sentinel.md
@@ -0,0 +1,4 @@
+## 2026-06-27 - [Insecure Deserialization in Utils.readSerializable]
+**Vulnerability:** In `me.desair.tus.server.util.Utils.readSerializable`, the code previously used an unrestricted `ObjectInputStream` to deserialize objects from a file on disk. This is a potential risk for arbitrary code execution if an attacker is able to upload a maliciously crafted serialized object and have it processed by the server, as the internal state objects (like `UploadInfo`) are serialized and deserialized to disk.
+**Learning:** Java object deserialization is inherently insecure when deserializing untrusted data. Using an unrestricted `ObjectInputStream` opens the application to a wide range of deserialization attacks, even if the stream source is a local file, if that file can be influenced by an attacker (e.g., via a file upload vulnerability).
+**Prevention:** Always use `org.apache.commons.io.serialization.ValidatingObjectInputStream` (or implement a custom `ObjectInputStream` that overrides `resolveClass`) to explicitly allow-list accepted classes or packages. The allow-list should be as narrow as possible (e.g., `java.lang.*`, `java.util.*`, and specific application packages).
diff --git a/src/main/java/me/desair/tus/server/util/Utils.java b/src/main/java/me/desair/tus/server/util/Utils.java
index e72af32..2fa3541 100644
--- a/src/main/java/me/desair/tus/server/util/Utils.java
+++ b/src/main/java/me/desair/tus/server/util/Utils.java
@@ -8,7 +8,6 @@
 import jakarta.servlet.http.HttpServletRequest;
 import java.io.BufferedOutputStream;
 import java.io.IOException;
-import java.io.ObjectInputStream;
 import java.io.ObjectOutput;
 import java.io.ObjectOutputStream;
 import java.io.OutputStream;
@@ -22,6 +21,7 @@
 import java.util.regex.Pattern;
 import me.desair.tus.server.HttpHeader;
 import me.desair.tus.server.checksum.ChecksumAlgorithm;
+import org.apache.commons.io.serialization.ValidatingObjectInputStream;
 import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -83,7 +83,9 @@ public static <T> T readSerializable(Path path, Class<T> clazz) throws IOExcepti
         // Lock will be released when the channel is closed
         if (lockFileShared(channel) != null) {
 
-          try (ObjectInputStream ois = new ObjectInputStream(Channels.newInputStream(channel))) {
+          try (ValidatingObjectInputStream ois =
+              new ValidatingObjectInputStream(Channels.newInputStream(channel))) {
+            ois.accept("java.lang.*", "java.util.*", "me.desair.tus.server.*");
             info = clazz.cast(ois.readObject());
           } catch (ClassNotFoundException
               | java.io.EOFException