From 9d4e3462f17d135b5c928e2419a17bd444c3f2b4 Mon Sep 17 00:00:00 2001
From: Michael Simacek <msimacek@redhat.com>
Date: Mon, 19 Mar 2018 16:01:57 +0100
Subject: [PATCH] Disallow EventData deserialization by default

---
 .../src/main/java/org/slf4j/ext/EventData.java     | 23 +++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/slf4j-ext/src/main/java/org/slf4j/ext/EventData.java b/slf4j-ext/src/main/java/org/slf4j/ext/EventData.java
index 4478e52..535c5c0 100644
--- a/slf4j-ext/src/main/java/org/slf4j/ext/EventData.java
+++ b/slf4j-ext/src/main/java/org/slf4j/ext/EventData.java
@@ -76,13 +76,22 @@ public class EventData implements Serializable {
    */
   @SuppressWarnings("unchecked")
   public EventData(String xml) {
-    ByteArrayInputStream bais = new ByteArrayInputStream(xml.getBytes());
-    try {
-      XMLDecoder decoder = new XMLDecoder(bais);
-      this.eventData = (Map<String, Object>) decoder.readObject();
-    } catch (Exception e) {
-      throw new EventException("Error decoding " + xml, e);
-    }
+      if ("1".equals(System.getProperty("org.slf4j.ext.allowInsecureDeserialization"))) {
+          ByteArrayInputStream bais = new ByteArrayInputStream(xml.getBytes());
+          try {
+              XMLDecoder decoder = new XMLDecoder(bais);
+              this.eventData = (Map<String, Object>) decoder.readObject();
+          } catch (Exception e) {
+              throw new EventException("Error decoding " + xml, e);
+          }
+      } else {
+          throw new UnsupportedOperationException(
+                  "Constructing EventData from XML is vulnerable to remote " +
+                  "excution and is not allowed by default. If you're " +
+                  "completely sure the source data is trusted, you can enable " +
+                  "it by setting org.slf4j.ext.allowInsecureDeserialization " +
+                  "JVM property to 1");
+      }
   }
 
   /**
-- 
2.14.3