GitHub Advisoryadvisory · Maven

GHSA-w35j-pv5h-q9q9 Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout

MEDIUM Published 2026-04-10 Modified 2026-04-13 Official page ↗
Aliases
CVE-2026-34481
Ecosystem
Maven
Packages
org.apache.logging.log4j:log4j-layout-template-json
Severity
Moderate
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
Weaknesses
CWE-116
Reviewed
2026-04-10

Affected packages

• Maven org.apache.logging.log4j:log4j-layout-template-json: >= 2.14.0, < 2.25.4 → fixed in 2.25.4 • Maven org.apache.logging.log4j:log4j-layout-template-json: >= 3.0.0-alpha1, <= 3.0.0-beta3 (no fix yet)

Description

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 `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.

Related

Alias · CVE (1)

  • CVE-2026-34481 Apache Log4j's JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including… vulnerability

Weakness · CWE (1)

  • CWE-116 Improper Encoding or Escaping of Output weakness

References