Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout
Apache Log4j's JsonTemplateLayout, 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
MapMessagecontaining an attacker-controlled floating-point value.
Users are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.apache.logging.log4j:log4j-layout-template-json | >= 2.14.0, < 2.25.4, >= 3.0.0-alpha1, <= 3.0.0-beta3 | 2.25.4 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-34481
- https://github.com/apache/logging-log4j2/pull/4080
- https://github.com/apache/logging-log4j2
- https://lists.apache.org/thread/n34zdv00gbkdbzt2rx9rf5mqz6lhopcv
- https://logging.apache.org/cyclonedx/vdr.xml
- https://logging.apache.org/log4j/2.x/manual/json-template-layout.html
- https://logging.apache.org/security.html#CVE-2026-34481
- http://www.openwall.com/lists/oss-security/2026/04/10/10
- CVSS 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- Weakness (CWE)
CWE-116- Platform
- Java / Kotlin (Maven)
- Package
org.apache.logging.log4j:log4j-layout-template-json- Disclosed
- 10.04.2026
- Updated
- 11.10.2026 13:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-w35j-pv5h-q9q9 - CC BY 4.0
Vulnerability history: org.apache.logging.log4j:log4j-layout-template-json
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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