Code execution via attacker-selected class initialization
Published Oct 19, 2026 · Updated Oct 19, 2026
Unsafe reflection in Apache Johnzon ClassConverter allows attackers to trigger class initialization through untrusted JSON. ClassConverter.fromString passes an unchecked class name to Class.forName with initialization enabled, executing the selected class's static initializer. Remote exploitation requires a REST model with a Class attribute and a hazardous initializer already on the application's classpath; consequences depend on that initializer's behavior.
Summary
What happened
Unsafe reflection in Apache Johnzon ClassConverter allows attackers to trigger class initialization through untrusted JSON. ClassConverter.fromString passes an unchecked class name to Class.forName with initialization enabled, executing the selected class's static initializer. Remote exploitation requires a REST model with a Class attribute and a hazardous initializer already on the application's classpath; consequences depend on that initializer's behavior.
The record
- CVE
- CVE-2026-71253
- Published
- Oct 19, 2026
- Updated
- Oct 19, 2026
- Vendor
- The Apache Software Foundation
- Product
- Apache Johnzon
- Classifications
- CWE-470
- Attack vector
- network
- Privileges
- Unavailable
Timeline
How it unfolded
- Oct 19, 2026CVE publishedPublication date reported by the CVE source.
- Oct 19, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=1.0.0 <1.3.1
- Affected versionversion=2.0.0 <2.2.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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