Improper Handling of Unexpected Data Type Affecting log4j:2/log4j-jcl package, versions *


Severity

Recommended
0.0
medium
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.12% (31st percentile)

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  • Snyk IDSNYK-RHEL8-LOG4J-16074332
  • published15 Apr 2026
  • disclosed10 Apr 2026

Introduced: 10 Apr 2026

NewCVE-2026-34481  (opens in a new tab)
CWE-241  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:8 log4j:2/log4j-jcl.

NVD Description

Note: Versions mentioned in the description apply only to the upstream log4j:2/log4j-jcl package and not the log4j:2/log4j-jcl package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

Apache Log4j's JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values (NaN, Infinity, or -Infinity), which are prohibited by RFC 8259. This may cause downstream log processing systems to reject or fail to index affected records.

An attacker can exploit this issue only if both of the following conditions are met:

  • The application uses JsonTemplateLayout.
  • The application logs a MapMessage containing an attacker-controlled floating-point value.

Users are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue.

CVSS Base Scores

version 3.1