2049 vulnerabilities classified as CWE-434 (危险类型文件的不加限制上传). AI Chinese analysis included.
CWE-434 represents a critical input validation weakness where applications permit the upload of file types that are inherently dangerous or automatically processed by the system. Attackers typically exploit this vulnerability by uploading malicious scripts, such as web shells or executable binaries, disguised as legitimate documents or images. Once uploaded, these files are executed by the server, granting the attacker remote code execution capabilities and potentially full system compromise. To mitigate this risk, developers must implement strict allowlists that define only the specific, safe file extensions permitted for upload. Additionally, files should be stored outside the web root directory to prevent direct execution, and content verification techniques, such as checking file headers rather than relying solely on extensions, should be employed to ensure integrity and prevent evasion of basic validation checks.
<form action="upload_picture.php" method="post" enctype="multipart/form-data"> Choose a file to upload: <input type="file" name="filename"/> <br/> <input type="submit" name="submit" value="Submit"/> </form>// Define the target location where the picture being // uploaded is going to be saved. $target = "pictures/" . basename($_FILES['uploadedfile']['name']); // Move the uploaded file to the new location. if(move_uploaded_file($_FILES['uploadedfile']['tmp_name'], $target)) { echo "The picture has been successfully uploaded."; } else { echo "There was an error uploading the picture, please try again."; }<form action="FileUploadServlet" method="post" enctype="multipart/form-data"> Choose a file to upload: <input type="file" name="filename"/> <br/> <input type="submit" name="submit" value="Submit"/> </form>public class FileUploadServlet extends HttpServlet { ... protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); String contentType = request.getContentType(); // the starting position of the boundary header int ind = contentType.indexOf("boundary="); String boundary = contentType.substring(ind+9); String pLine = new String(); String uploadLocation = new String(UPLOAD_DIRECTORY_STRING); //Constant value // verify that content type is multipart form data iVulnerabilities classified as CWE-434 (危险类型文件的不加限制上传) represent 2049 CVEs. The CWE taxonomy describes the weakness; review individual CVEs for product-specific impact.