CVE-2026-71253

Critical

Description

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.

SeverityCritical

CVSS9.8

Exploit probability—

ProductApache Johnzon

PublishedOct 19, 2026

First seenOct 19, 2026

Weakness typeCWE-470CWE-470

How to fix

Update

Apache Software Foundation Apache Johnzon2.2.0, 1.3.1 or later

Patches

Vendor advisories

lists.apache.org/thread.html/3vgm1yo2sn9yhkvvs9lc4ro01vl3zt68

Affected products

Product	Affected versions	Fixed in
Apache Software Foundation Apache Johnzon	2.0.0 ≤ v < 2.2.0, 1.0.0 ≤ v < 1.3.1	2.2.0, 1.3.1

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