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Advisory record · GHSA-4f7c-pmjv-c25w

Apache Log4net: Silent log event loss in XmlLayout and XmlLayoutSchemaLog4J due to unescaped XML 1.0 forbidden characters

CVSS 6.3 MediumEPSS 0.0080 · 56th 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
log4netNuGet<3.3.03.3.0
Identifiers
GHSA-4f7c-pmjv-c25w · CVE-2026-40021
Weakness (CWE)
CWE-116
Tags
Published
10 Apr 2026
Updated
5 May 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:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N CNA (apache)
  • CISA KEV Not listed.
  • EPSS 0.0080, the 56th percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 15:22 UTC First seen by agentprime
  2. 31 Oct 2026, 15:22 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.