CVE-2026-71253

Apache Johnzon: ClassConverter loads & static-initializes an attacker-named class from untrusted JSON

Apache Software Foundation Apache Johnzon

CVSS

9.8Critical

ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV

Exploit odds (EPSS)0.65%Chance of exploitation activity in the next 30 days, higher than 50% of CVEs. Scored 23 Oct 2026FIRST EPSS

Fixed in2.2.0Also 1.3.1CVE List

Published19 Oct 2026Updated 20 Oct 2026CVE List

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') vulnerability in Apache Johnzon.

ClassConverter loads & static-initializes an attacker-named class from untrusted JSON.

This issue affects Apache Johnzon: from 1.0.0 before 2.2.0.

Users are recommended to upgrade to version 1.3.1 (javax namespace) or 2.2.0 (jakarta specification namespace), which fixes the issue.

Text from CVE List