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.

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History

Fri, 10 Apr 2026 18:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 10 Apr 2026 17:30:00 +0000

Type Values Removed Values Added
References

Fri, 10 Apr 2026 16:00:00 +0000

Type Values Removed Values Added
Description 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.
Title Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout
First Time appeared Apache
Apache log4j Layout Template Json
Weaknesses CWE-116
CPEs cpe:2.3:a:apache:log4j_layout_template_json:*:*:*:*:*:*:*:*
Vendors & Products Apache
Apache log4j Layout Template Json
References
Metrics cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-04-10T17:41:38.229Z

Reserved: 2026-03-28T19:23:37.127Z

Link: CVE-2026-34481

cve-icon Vulnrichment

Updated: 2026-04-10T16:18:20.891Z

cve-icon NVD

Status : Received

Published: 2026-04-10T16:16:31.663

Modified: 2026-04-10T17:17:02.747

Link: CVE-2026-34481

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses