CVE-2026-34477
Published:April 10, 2026
Updated:April 17, 2026
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.
Affected Packages
https://github.com/apache/logging-log4j2.git (GITHUB):
Affected version(s) >=rel/2.12.0 <rel/2.25.4Fix Suggestion:
Update to version rel/2.25.4org.apache.logging.log4j:log4j-core (JAVA):
Affected version(s) >=2.12.0 <2.25.4Fix Suggestion:
Update to version 2.25.4org.apache.logging.log4j:log4j-core (JAVA):
Affected version(s) >=2.12.0 <2.25.4Fix Suggestion:
Update to version 2.25.4Related Resources (8)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.3
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
NONE
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
LOW
Subsequent System Availability
NONE
CVSS v3
Base Score:
4
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Weakness Type (CWE)
Improper Validation of Certificate with Host Mismatch
EPSS
Base Score:
0.11