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[ CVE-2026-34477 · Published 10 Apr 2026 ]

Vulnerability in Apache Software Foundation Apache Log4j Core

CVSS 6.3 EPSS <1%3 agency advisoriesNo fix listed yet

[ Description ]Official description

The fix for CVE-2025-68161 https://logging.apache.org/security.html#CVE-2025-68161 was incomplete: it addressed hostname verification only when enabled via the log4j2.sslVerifyHostName https://logging.apache.org/log4j/2.x/manual/systemproperties.html#log4j2.sslVerifyHostName system property, but not when configured through the verifyHostName https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName attribute of the <Ssl> element. Although the verifyHostName configuration attribute was introduced in Log4j Core 2.12.0, it was silently ignored in all versions through 2.25.3, leaving TLS connections vulnerable to interception regardless of the configured value. A network-based attacker may be able to perform a man-in-the-middle attack when all of the following conditions are met: * An SMTP, Socket, or Syslog appender is in use. * TLS is configured via a nested <Ssl> element. * The attacker can present a certificate issued by a CA trusted by the appender's configured trust store, or by the default Java trust store if none is configured. This issue does not affect users of the HTTP appender, which uses a separate verifyHostname https://logging.apache.org/log4j/2.x/manual/appenders/network.html#HttpAppender-attr-verifyHostName attribute that was not subject to this bug and verifies host names by default. Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

  • NCSC-NLNCSC-2026-0448

    Vulnerabilities fixed in Oracle Fusion Middleware Translated from Dutch

    Probability/damage H/HCVE-2026-54513CVE-2026-56741CVE-2026-59649+191 more CVEs
  • BSI CERT-BundWID-SEC-2026-4078

    Oracle Fusion Middleware: Multiple vulnerabilities Translated from German

    CVE-2026-91212CVE-2023-43622CVE-2026-42779+191 more CVEs
  • CERT-FRCERTFR-2026-AVI-1256

    Multiple vulnerabilities in IBM products Translated from French

    Multiple vulnerabilities have been discovered in IBM products. Some of them allow an attacker to cause remote arbitrary code execution, privilege escalation and remote denial of service.

    CVE-2026-27980CVE-2026-58055CVE-2026-49978+360 more CVEs

[ References ]References