GitHub Advisoryadvisory · Maven
GHSA-w35j-pv5h-q9q9 Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout
MEDIUM
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
- https://nvd.nist.gov/vuln/detail/CVE-2026-34481 advisory
- https://github.com/apache/logging-log4j2/pull/4080 web
- https://github.com/apache/logging-log4j2 package
- https://lists.apache.org/thread/n34zdv00gbkdbzt2rx9rf5mqz6lhopcv web
- https://logging.apache.org/cyclonedx/vdr.xml web
- https://logging.apache.org/log4j/2.x/manual/json-template-layout.html web
- https://logging.apache.org/security.html#CVE-2026-34481 web
- http://www.openwall.com/lists/oss-security/2026/04/10/10 web