CVE-2021-22144: 
Java vulnerability analysis and mitigation

An uncontrolled recursion vulnerability (CVE-2021-22144) was identified in the Elasticsearch Grok parser affecting versions before 7.13.3 and 6.8.17. The vulnerability was discovered in July 2021 and could lead to a denial of service attack. The issue affects Elasticsearch installations where users have the ability to submit arbitrary queries (Elastic Discussion).

The vulnerability is classified as an uncontrolled recursion issue (CWE-674) with a CVSS v3.1 base score of 6.5 (MEDIUM), and vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. The vulnerability requires low attack complexity and low privileges to exploit, with no user interaction needed (NVD).

If successfully exploited, the vulnerability allows an attacker to create a malicious Grok query that will crash the Elasticsearch node, resulting in a denial of service condition. This impacts the availability of the Elasticsearch service (Elastic Discussion).

The vulnerability can be exploited by a user with the ability to submit arbitrary queries to Elasticsearch. The attacker needs to craft a specific malicious Grok query to trigger the uncontrolled recursion condition (NVD).

Users should upgrade their Elasticsearch installations to version 7.13.3 or 6.8.17 or later versions to address this vulnerability. No alternative workarounds have been provided (Elastic Discussion).