Advisory severityMedium6.3Apache Software Foundation

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

This medium-severity Apache Software Foundation advisory covers CVE-2026-34481 affecting Apache Log4j, Apache Log4j JSON, Log4j.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-34481 Source published Apr 10, 2026Source updated Jun 17, 2026

VulniPulse record published Jul 11, 2026

CVE-2026-34481

Affected products & platforms

Apache Software FoundationLog4j

Open source advisory

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Summary

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.

Affected versions

2.25.3

Official advisory · high-confidence parse· fetched 3 months ago·verify at source

Fixed versions

2.25.4

Official advisory · high-confidence parse· fetched 3 months ago·verify at source

Mitigation

Upgrade to a fixed release: 2.25.4. That is the remediation for this advisory.

The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.

Official advisory · high-confidence parse· fetched 3 months ago·verify at source

Sources

Official and corroborating records used to build this advisory.

NVD discovery recordNVD
Independent discovery and scoring cross-reference. Vendor remediation guidance takes precedence. Discovered from the machine-readable feed https://services.nvd.nist.gov/rest/json/cves/2.0; this link opens the NVD record for CVE-2026-34481 instead of the raw feed document.
NIST National Vulnerability Database

Cross-references

Validate CVE metadata against the authoritative registries.

CVE-2026-34481NVD CVE.org MITRE

Official resources

ASF Security — reporting & CVE process
Official documentation
The Apache Software Foundation's official security page: how ASF CVEs are published and where each project's advisories live.
Apache project downloads (fixed releases)
Official documentation
Official ASF download tree — fetch the fixed release named in this advisory from the project's directory.

Discussion(0)

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