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Advisory record · GHSA-w35j-pv5h-q9q9

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

CVSS 6.3 MediumEPSS 0.0072 · 54th percentile

Published by the GitHub Advisory Database at 10 Apr 2026, 18:31 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
org.apache.logging.log4j:log4j-layout-template-jsonMaven>=2.14.0, <2.25.4 || >=3.0.0-alpha1, <=3.0.0-beta32.25.4
Identifiers
GHSA-w35j-pv5h-q9q9 · CVE-2026-34481
Weakness (CWE)
CWE-116
Tags
Published
10 Apr 2026
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Apache Log4j's log4j-layout-template-json, versions 2.14.0 up to 2.25.4 (excluding 2.25.4) and 3.0.0-alpha1 through 3.0.0-beta3, produces invalid JSON when log events contain NaN, Infinity, or -Infinity values. An attacker who can supply a floating-point value that the application logs through a MapMessage, in an application using JsonTemplateLayout, can cause downstream log processors to reject or fail to index those records. Upgrade to log4j-layout-template-json 2.25.4.

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
6.3 Medium 4.0 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 CNA (apache)
  • CISA KEV Not listed.
  • EPSS 0.0072, the 54th percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:16 UTC First seen by agentprime
  2. 31 Oct 2026, 14:16 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.