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CRITICAL

CVE-2026-71253

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

CVSS v3

9.8

CRITICAL

EPSS Score

0.7 %

exploit probability, as of 2026-10-22

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2026-71253 Red Hat Product Security1 known affected

    org.apache.johnzon/johnzon-mapper: Apache Johnzon: Arbitrary code execution via unsafe class loading

    johnzon-mapper as a component of Red Hat Fuse 7

Full record on NVD

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.

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2026-10-19
Last Modified
2026-10-20

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.

Is CVE-2026-71253 actively exploited?

Active exploitation of CVE-2026-71253 has not been confirmed. Its EPSS score was 0.7% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-71253?

CVE-2026-71253 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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