CVE-2026-71253 (CVSS 9.8)

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.

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CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0038

Probability of exploitation

0.32%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-470 CWE-470

References

Other References

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

Frequently Asked Questions

What is CVE-2026-71253? +

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. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-71253? +

CVE-2026-71253 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0038, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-71253? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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