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= 2.17.1 (2021-12-27)

This release addresses CVE-2021-44832 and contains other minor fixes.

Due to a break in compatibility in the SLF4J binding, Log4j now ships with two versions of the SLF4J to Log4j adapters.
`log4j-slf4j-impl` should be used with SLF4J 1.7.x and earlier and `log4j-slf4j18-impl` should be used with SLF4J 1.8.x and later.
SLF4J-2.0.0 alpha releases are not fully supported.
See https://issues.apache.org/jira/browse/LOG4J2-2975[LOG4J2-2975] and https://jira.qos.ch/browse/SLF4J-511[SLF4J-511].

The Log4j 2.17.1 API, as well as many core components, maintains binary compatibility with previous releases.

Apache Log4j 2.17.1 requires a minimum of Java 8 to build and run.
Log4j 2.12.2 is the last release to support Java 7.
Java 7 is no longer supported by the Log4j team.

For complete information on Apache Log4j 2, including instructions on how to submit bug reports, patches, or suggestions for improvement, see http://logging.apache.org/log4j/2.x/[the Apache Log4j 2 website].


[#release-notes-2-17-1-fixed]
=== Fixed

* Fix NPE when input is null in StrSubstitutor.replace(String, Properties).
* Correct SpringLookup package name in Interpolator. (https://issues.apache.org/jira/browse/LOG4J2-3204[LOG4J2-3204])
* Reduce ignored package scope of KafkaAppender. (https://issues.apache.org/jira/browse/LOG4J2-3256[LOG4J2-3256])
* Fix MapLookup to lookup MapMessage before DefaultMap (https://issues.apache.org/jira/browse/LOG4J2-3264[LOG4J2-3264])
* Lookups with no prefix only read values from the configuration properties as expected. (https://issues.apache.org/jira/browse/LOG4J2-3270[LOG4J2-3270])
* Buffered I/O checked had inverted logic in RollingFileAppenderBuilder. (https://issues.apache.org/jira/browse/LOG4J2-3274[LOG4J2-3274])
* log4j-to-slf4j takes the provided MessageFactory into account (https://issues.apache.org/jira/browse/LOG4J2-3284[LOG4J2-3284])
* log4j-to-slf4j no longer re-interpolates formatted message contents. (https://issues.apache.org/jira/browse/LOG4J2-3289[LOG4J2-3289])
* Remove unused method. (https://issues.apache.org/jira/browse/LOG4J2-3290[LOG4J2-3290])
* ExtendedLoggerWrapper.logMessage no longer double-logs when location is requested. (https://issues.apache.org/jira/browse/LOG4J2-3292[LOG4J2-3292])
* JdbcAppender now uses JndiManager to access JNDI resources. JNDI is only enabled when system property log4j2.enableJndiJdbc is set to true. (https://issues.apache.org/jira/browse/LOG4J2-3293[LOG4J2-3293])
