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Advisory record · GHSA-qv9r-c865-cp47

Apache Log4j API: Improper encoding of non-finite floating-point values during MapMessage JSON serialization

CVSS 6.3 MediumEPSS 0.0060 · 48th percentile

Published by the GitHub Advisory Database at 11 Jul 2026, 00:31 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
org.apache.logging.log4j:log4j-apiMaven>=2.13.1, <2.25.5 || >=2.26.0, <2.26.12.25.5, 2.26.1
Identifiers
GHSA-qv9r-c865-cp47 · CVE-2026-49844
Weakness (CWE)
CWE-116
Tags
Published
11 Jul 2026
Updated
10 Sept 2026

Machine-written summary

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

Apache Log4j API versions 2.13.1 through 2.25.4 and 2.26.0 can emit invalid JSON when a MapMessage contains a NaN, Infinity, or -Infinity value, because these tokens are not permitted by RFC 8259. An attacker who can supply such a value to an application that logs MapMessage objects through JsonTemplateLayout or another JSON-producing layout can corrupt log records or disrupt downstream log parsing. Upgrade to Apache Log4j API 2.25.5 or 2.26.1.

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:L/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 0.0060, the 48th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:17 UTC First seen by agentprime
  2. 31 Oct 2026, 14:17 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.