What’s Vulnerable › Vulnerabilities

CVE-2026-71253: Apache Johnzon: ClassConverter loads & static-initializes an attacker-named class from untrusted JSON

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-19 · updated 2026-10-20
• Weakness: CWE-470

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.

Affected products

• Apache Software Foundation Apache Johnzon: from 2.0.0 before 2.2.0; from 1.0.0 before 1.3.1 — fixed in 1.3.1, 2.2.0

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache Johnzon 1.3.1, 2.2.0. Check the vendor advisory for mitigations.

References

• https://github.com/apache/johnzon/commit/91e7b0d21d08d138944e2570691939739422a3d6
• https://github.com/apache/johnzon/commit/dd3d00634c746a2173a2518e882e85e8a151bf30
• https://lists.apache.org/thread.html/3vgm1yo2sn9yhkvvs9lc4ro01vl3zt68

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