Improper Validation of Certificate with Host Mismatch Affecting org.apache.logging.log4j:log4j-core package, versions [2.12.0, 2.25.4)[3.0.0-alpha1,]
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JAVA-ORGAPACHELOGGINGLOG4J-15967727
- published10 Apr 2026
- disclosed10 Apr 2026
- creditSamuli Leinonen
Introduced: 10 Apr 2026
CVE-2026-34477 (opens in a new tab)How to fix?
A fix was pushed into the master branch but not yet published.
Overview
org.apache.logging.log4j:log4j-core is a logging library for Java.
Affected versions of this package are vulnerable to Improper Validation of Certificate with Host Mismatch due to the lack of TLS hostname verification in the SocketAppender component when configured through the verifyHostName attribute of the <Ssl> element. An attacker can intercept and manipulate network traffic by presenting a certificate issued by a trusted certificate authority to the appender's configured trust store, or the default Java trust store if none is configured. This is only exploitable if an SMTP, Socket, or Syslog appender is in use and TLS is configured via a nested element.
Note:
This issue is due to incomplete fix for CVE-2025-68161.