Unsafe reflection in Apache Johnzon - CVE-2026-71253
Published: October 23, 2026
Vulnerability identifier: #VU157319
CSH Severity: Medium
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-71253
CWE-ID: CWE-470
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to trigger execution of static initializer code in an attacker-selected class.
The vulnerability exists due to unsafe reflection in Apache Johnzon's ClassConverter when deserializing untrusted JSON. A remote attacker can supply JSON containing a chosen class name to cause that class to be loaded and its static initializer to execute.
Exploitation requires a class with a harmful static initializer already on the application's classpath and a REST POJO with a Class attribute.
Affected software
Apache Johnzon
How to mitigate CVE-2026-71253
Install security update from vendor's website.
Apache Johnzon - update to 1.3.1