diff --git a/test/extensions/filters/http/ext_proc/unit_test_fuzz/ext_proc_corpus/crash-2f5c31257230464b4b6015ecee3f6f090547fb0a b/test/extensions/filters/http/ext_proc/unit_test_fuzz/ext_proc_corpus/crash-2f5c31257230464b4b6015ecee3f6f090547fb0a
new file mode 100644
index 000000000000..8cb2340a494d
--- /dev/null
+++ b/test/extensions/filters/http/ext_proc/unit_test_fuzz/ext_proc_corpus/crash-2f5c31257230464b4b6015ecee3f6f090547fb0a
@@ -0,0 +1,43 @@
+config {
+  grpc_service {
+    envoy_grpc {
+      cluster_name: "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+    }
+  }
+  response_attributes: "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+  response_attributes: "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+  mutation_rules {
+    allow_expression {
+      regex: "!"
+    }
+  }
+  max_message_timeout {
+  }
+}
+request {
+}
+response {
+  request_body {
+  }
+  dynamic_metadata {
+    fields {
+      key: ""
+      value {
+        list_value {
+          values {
+            bool_value: false
+          }
+        }
+      }
+    }
+    fields {
+      key: ""
+      value {
+        string_value: ""
+      }
+    }
+  }
+  mode_override {
+    request_trailer_mode: SEND
+  }
+}
diff --git a/test/extensions/filters/http/ext_proc/unit_test_fuzz/ext_proc_unit_test_fuzz.cc b/test/extensions/filters/http/ext_proc/unit_test_fuzz/ext_proc_unit_test_fuzz.cc
index 2c565386cd91..89d6c55c9069 100644
--- a/test/extensions/filters/http/ext_proc/unit_test_fuzz/ext_proc_unit_test_fuzz.cc
+++ b/test/extensions/filters/http/ext_proc/unit_test_fuzz/ext_proc_unit_test_fuzz.cc
@@ -51,6 +51,11 @@ DEFINE_PROTO_FUZZER(
       input.config();
   ExternalProcessing::FilterConfigSharedPtr config;
 
+  // Create regex engine which is used by regex matcher code.
+  Regex::EnginePtr regex_engine = std::make_shared<Regex::GoogleReEngine>();
+  Regex::EngineSingleton::clear();
+  Regex::EngineSingleton::initialize(regex_engine.get());
+
   try {
     config = std::make_shared<ExternalProcessing::FilterConfig>(
         proto_config, std::chrono::milliseconds(200), 200, *stats_store.rootScope(),