feat: support Freemarker SpEL packer

vul/vul-springboot3/build.gradle.kts

@@ -22,6 +22,7 @@ dependencies {
     implementation("ognl:ognl:2.7.3")
     implementation("commons-jxpath:commons-jxpath:1.3")
     implementation("commons-beanutils:commons-beanutils:1.9.3")
+    implementation("org.freemarker:freemarker:2.3.23")
 }
 
 tasks.test {

vul/vul-springboot3/src/main/java/com/reajason/javaweb/vul/springboot3/controller/FreemarkerController.java

@@ -0,0 +1,35 @@
+package com.reajason.javaweb.vul.springboot3.controller;
+
+import freemarker.template.Configuration;
+import freemarker.template.Template;
+import freemarker.template.TemplateException;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.io.StringWriter;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * @author ReaJason
+ * @since 2026/8/30
+ */
+@RestController
+@RequestMapping("/freemarker")
+public class FreemarkerController {
+    @PostMapping
+    public String freemarker(@RequestParam String data) throws IOException, TemplateException {
+        Configuration configuration = new Configuration();
+        configuration.setDefaultEncoding("UTF-8");
+        Map<String, Object> input = new HashMap<>();
+        input.put("object", new Object());
+        Template template = new Template("templateName", new StringReader(data), configuration);
+        StringWriter output = new StringWriter();
+        template.process(input, output);
+        return output.toString();
+    }
+}