CVE-2026-71253 Apache Johnzon: ClassConverter loads & static-initializes an attacker-named class from untrusted JSON
Attacker can execute arbitrary code via unsafe reflection in Apache Johnzon by providing malicious JSON input.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-71253?
CVE-2026-71253 is a critical code injection vulnerability in Apache Johnzon, published on 19 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-470
Which versions are affected by CVE-2026-71253?
How do I fix CVE-2026-71253?
No fix has been published for CVE-2026-71253 yet. Limit exposure of the affected software until one is available.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-71253 being exploited?
There is no known exploitation of CVE-2026-71253 in the wild and no public exploit code.
Sources
Also known as GHSA-66gj-8qvf-qvfh.