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Advisory record · GHSA-6hg6-v5c8-fphq

Apache Log4j Core: `verifyHostName` attribute silently ignored in TLS configuration

CVSS 6.3 MediumEPSS 0.0057 · 47th 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-coreMaven>=2.12.0, <2.25.4 || >=3.0.0-alpha1, <=3.0.0-beta32.25.4
Identifiers
GHSA-6hg6-v5c8-fphq · CVE-2026-34477
Weakness (CWE)
CWE-297
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 Core versions 2.12.0 up to 2.25.4 (exclusive), and 3.0.0-alpha1 through 3.0.0-beta3, silently ignore the verifyHostName attribute in TLS configuration for SMTP, Socket, and Syslog appenders. An attacker with network access who can present a certificate from a CA trusted by the appender's trust store may be able to perform a man-in-the-middle attack on those TLS connections. Upgrade to Apache Log4j Core 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:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:L/SA:N CNA (apache)
  • CISA KEV Not listed.
  • EPSS 0.0057, the 47th percentile, on 11 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.