CVE-2026-34481: Apache Log4j JSON Template Layout Improper Serialization Of Non-finite Floating-point Vulnerability
MODERATECVE-2026-34481 is a MODERATE improper serialization of non-finite floating-point vulnerability (CWE-116: Improper Encoding or Escaping of Output) affecting Apache Log4j JSON Template Layout libraries in the Maven ecosystem. The issue involves improper serialization of non-finite floating-point values in jsontemplatelayout. Remediation is available by upgrading affected packages to version 2.25.4.
CVE-2026-34481 at a Glance
How to Fix CVE-2026-34481
To remediate this vulnerability, upgrade all affected Apache Log4j JSON Template Layout dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-layout-template-json</artifactId>
<version>2.25.4</version>
</dependency><dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-layout-template-json</artifactId>
<version>Latest secure release</version>
</dependency>Run the following command in your project directory to verify that all resolved dependencies use the patched release:
mvn dependency:tree -Dincludes=org.apache.logging.log4jHow to Check if You Are Affected
To determine whether your Java application is affected by CVE-2026-34481, inspect your build dependencies using the Maven Dependency Plugin:
mvn dependency:tree -Dincludes=org.apache.logging.log4jAnalyze the terminal output to locate any version of Apache Log4j JSON Template Layout in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.25.4), your application is affected.
Note: The mvn dependency:tree -Dincludes=org.apache.logging.log4j command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-116: Improper Encoding or Escaping of Output, where the product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. as a result, the intended structure of the message is not preserved. In Apache Log4j JSON Template Layout, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-34481 Affected Apache Log4j JSON Template Layout Versions
2 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
org.apache.logging.log4j:log4j-layout-template-json
|
Maven |
≥ 2.14.0
< 2.25.4
|
2.25.4
|
|
org.apache.logging.log4j:log4j-layout-template-json
|
Maven |
≥ 3.0.0-alpha1
≤ 3.0.0-beta3
|
|
References
Frequently Asked Questions
What is CVE-2026-34481?
Which Apache Log4j JSON Template Layout versions are affected?
What version fixes CVE-2026-34481?
Is log4j-layout-template-json affected?
What CWE is associated with CVE-2026-34481?
How can I check Maven dependencies for CVE-2026-34481?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-w35j-pv5h-q9q9",
"modified" : "2026-04-13T23:59:41Z",
"published" : "2026-04-10T18:31:18Z",
"aliases" : [ "CVE-2026-34481" ],
"summary" : "Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout",
"details" : "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.\n\nAn attacker can exploit this issue only if both of the following conditions are met:\n\n * The application uses `JsonTemplateLayout`.\n * The application logs a `MapMessage` containing an attacker-controlled floating-point value.\n\nUsers are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue.",
"severity" : [ {
"type" : "CVSS_V4",
"score" : "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"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Maven",
"name" : "org.apache.logging.log4j:log4j-layout-template-json"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "2.14.0"
}, {
"fixed" : "2.25.4"
} ]
} ]
}, {
"package" : {
"ecosystem" : "Maven",
"name" : "org.apache.logging.log4j:log4j-layout-template-json"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "3.0.0-alpha1"
}, {
"last_affected" : "3.0.0-beta3"
} ]
} ]
} ],
"references" : [ {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34481"
}, {
"type" : "WEB",
"url" : "https://github.com/apache/logging-log4j2/pull/4080"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/apache/logging-log4j2"
}, {
"type" : "WEB",
"url" : "https://lists.apache.org/thread/n34zdv00gbkdbzt2rx9rf5mqz6lhopcv"
}, {
"type" : "WEB",
"url" : "https://logging.apache.org/cyclonedx/vdr.xml"
}, {
"type" : "WEB",
"url" : "https://logging.apache.org/log4j/2.x/manual/json-template-layout.html"
}, {
"type" : "WEB",
"url" : "https://logging.apache.org/security.html#CVE-2026-34481"
}, {
"type" : "WEB",
"url" : "http://www.openwall.com/lists/oss-security/2026/04/10/10"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-116" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2026-04-10T21:16:54Z",
"nvd_published_at" : "2026-04-10T16:16:31Z"
}
}