Package Instance

Apache Log4j does not verify the TLS hostname in its Socket Appender
The Socket Appender in Apache Log4j Core versions 2.0-beta9 through 2.25.2 does not perform TLS hostname verification of the peer certificate, even when the  [verifyHostName](https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName)  configuration attribute or the  [log4j2.sslVerifyHostName](https://logging.apache.org/log4j/2.x/manual/systemproperties.html#log4j2.sslVerifyHostName) system property is set to true.

This issue may allow a man-in-the-middle attacker to intercept or redirect log traffic under the following conditions:

*  The attacker is able to intercept or redirect network traffic between the client and the log receiver.
*  The attacker can present a server certificate issued by a certification authority trusted by the Socket Appender’s configured trust store (or by the default Java trust store if no custom trust store is configured).


Users are advised to upgrade to Apache Log4j Core version 2.25.3, which addresses this issue.

As an alternative mitigation, the Socket Appender may be configured to use a private or restricted trust root to limit the set of trusted certificates.

Apache Log4j 1.x (EOL) allows Denial of Service (DoS)
** UNSUPPORTED WHEN ASSIGNED ** When using the Chainsaw or SocketAppender components with Log4j 1.x on JRE less than 1.7, an attacker that manages to cause a logging entry involving a specially-crafted (ie deeply nested) hashmap or hashtable (depending on which logging component is in use) to be processed could exhaust the available memory in the virtual machine and achieve Denial of Service when the object is deserialized. This issue affects Apache Log4j before 2. Affected users are recommended to update to Log4j 2.x. NOTE: This vulnerability only affects products that are no longer supported by the maintainer.

Improper Input Validation and Injection in Apache Log4j2
Apache Log4j2 versions 2.0-beta7 through 2.17.0 (excluding security fix releases 2.3.2 and 2.12.4) are vulnerable to an attack where an attacker with permission to modify the logging configuration file can construct a malicious configuration using a JDBC Appender with a data source referencing a JNDI URI which can execute remote code. This issue is fixed by limiting JNDI data source names to the java protocol in Log4j2 versions 2.17.1, 2.12.4, and 2.3.2.