---
id: CVE-2026-34481
title: >-
  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…
summary: >-
  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…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N'
cwe:
  - CWE-116
  - CWE-241
vendor: apache
product: log4j
affected:
  - 'log4j >= 2.14.0, < 2.25.4'
  - log4j = 3.0.0
patched:
  - log4j 2.25.4
published: '2026-04-10'
updated: '2026-07-11'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-34481'
references:
  - url: 'https://github.com/apache/logging-log4j2/pull/4080'
    label: security@apache.org
  - url: 'https://lists.apache.org/thread/n34zdv00gbkdbzt2rx9rf5mqz6lhopcv'
    label: security@apache.org
  - url: 'https://logging.apache.org/cyclonedx/vdr.xml'
    label: security@apache.org
  - url: 'https://logging.apache.org/log4j/2.x/manual/json-template-layout.html'
    label: security@apache.org
  - url: 'https://logging.apache.org/security.html#CVE-2026-34481'
    label: security@apache.org
  - url: 'http://www.openwall.com/lists/oss-security/2026/04/10/10'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34481.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-34481'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2457321'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-34481'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-34481'
  - url: 'https://access.redhat.com/errata/RHSA-2026:22619'
  - url: 'https://access.redhat.com/errata/RHSA-2026:21773'
  - url: 'https://access.redhat.com/errata/RHSA-2026:37390'
  - url: 'https://access.redhat.com/errata/RHSA-2026:54435'
  - url: 'https://access.redhat.com/errata/RHSA-2026:66545'
  - url: 'https://access.redhat.com/errata/RHSA-2026:66488'
tags:
  - nvd
  - csaf
  - vex
  - red-hat
epss: 0.00854
epssPercentile: 0.56574
ingestedAt: '2026-07-11T07:12:24.000Z'
scores:
  nvd: 7.5
  vendor: 6.5
---

## Overview

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, or logs an object directly (e.g., via Logger.info(Object), which wraps it in an ObjectMessage), where the message contains an attacker-controlled floating-point value.


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

Note: The fix released in version 2.25.4 did not cover all affected code paths. CVE-2026-49844 was assigned to the remaining issue, which concerns the MapMessage.asJson() serialization in Apache Log4j API and is fixed in versions 2.25.5 and 2.26.1.

## Affected

- `log4j >= 2.14.0, < 2.25.4`
- `log4j = 3.0.0`

## Remediation

Upgrade past the affected range:

- `log4j 2.25.4`

## Vendor advisories

- **RHSA-2026:22619** · Red Hat · fixed in: Red Hat Data Grid 8.6.1 · released 2026-06-02 · [advisory](https://access.redhat.com/errata/RHSA-2026:22619)
- **RHSA-2026:21773** · Red Hat · fixed in: Red Hat Offline Knowledge Portal 1.2.12 · released 2026-05-28 · [advisory](https://access.redhat.com/errata/RHSA-2026:21773)
- **RHSA-2026:37390** · Red Hat · fixed in: Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16 · released 2026-07-09 · [advisory](https://access.redhat.com/errata/RHSA-2026:37390)
- **RHSA-2026:54435** · Red Hat · fixed in: Streams for Apache Kafka 3.2.1 · released 2026-08-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:54435)
- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 9, Red Hat JBoss Enterprise Application Platform 7 · no fix planned: Red Hat Enterprise Linux 9, Red Hat JBoss Enterprise Application Platform 7 · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34481.json)
- **RHSA-2026:66545** · Red Hat · fixed in: Red Hat AMQ Broker 7.13.6 · released 2026-09-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:66545)
- **RHSA-2026:66488** · Red Hat · fixed in: Red Hat AMQ Broker 7.14.1 · released 2026-09-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:66488)