greadle-127

title: "Java 21 Upgrade & Compatibility Analysis: Log4j 1.2.17 & Jackson Annotations 2.17.2"
published: true
tags: java, maven, gradle, security
canonical_url:Java 21 Upgrade & Compatibility AnalysisThis guide breaks down the compatibility, security risks, JVM runtime flags, and migration strategies for migrating Log4j 1.2.17 and Jackson Annotations 2.17.2 to Java 21.1. Artifact: log4j:log4j:1.2.17Overview & JDK TargetOriginal JDK Target: Java 1.4 (Class file major/minor version 48.0). Built to run on JDK 1.4 through JDK 8. Java 21 Behavior: When executing directly under Java 21 without upgrading, strong Java Platform Module System (JPMS) encapsulation blocks reflection into internal JDK APIs unless explicit command-line flags are configured. Critical Vulnerabilities & Security RisksLog4j 1.2.17 has been End-of-Life (EOL) since August 2015 and contains severe unpatched security vulnerabilities: CVE-2019-17571 (CVSS 9.8): Remote Code Execution (RCE) via untrusted deserialization in SocketServer. CVE-2021-4104: Deserialization vulnerability when configured to use JMSAppender. CVE-2022-23302: Deserialization vulnerability when configured to use JMSSink. CVE-2022-23305 (CVSS 9.8): SQL Injection in JDBCAppender. Temporary Workaround: JVM Command-Line FlagsIf you cannot immediately upgrade dependencies and must run unpatched log4j:log4j:1.2.17 on Java 21, pass these JVM flags to bypass encapsulation restrictions: Bash--add-opens=java.base/java.lang=ALL-UNNAMED
--add-opens=java.base/java.util=ALL-UNNAMED
-Dsun.util.logging.disableWindowWarning=true
⚠️ Warning: Passing --add-opens flags resolves Java 21 runtime IllegalAccessException or InaccessibleObjectException errors, but it does not patch or fix any of the severe security CVEs present in Log4j 1.2.17. Recommended Strategy: Migrate to Log4j 2.x BridgeWill upgrading require rewriting code calls?NO. Code calls do not need to be rewritten. The log4j-1.2-api bridge intercepts existing org.apache.log4j.* package imports and transparently routes all logging calls directly to the modern Log4j 2 engine. You only need to update build script dependencies and migrate configuration files (log4j.properties/.xml $\$rightarrow log4j2.xml). Maven Configuration XML

org.apache.logging.log4j
log4j-1.2-api
2.23.1


org.apache.logging.log4j
log4j-api
2.23.1


org.apache.logging.log4j
log4j-core
2.23.1


Gradle ConfigurationGroovydependencies {
implementation 'org.apache.logging.log4j:log4j-1.2-api:2.23.1'
implementation 'org.apache.logging.log4j:log4j-api:2.23.1'
implementation 'org.apache.logging.log4j:log4j-core:2.23.1'
}

1. Artifact: com.fasterxml.jackson.core:jackson-annotations:2.17.2Overview & JDK TargetOriginal JDK Target: Java 8 (Class file major version 52.0). Java 21 Compliance: Designed as a Multi-Release JAR (MRJAR) with complete Java Platform Module System (JPMS) descriptors (module-info.class under module name com.fasterxml.jackson.annotation). Fully tested, certified, and compliant with modern JVMs up to Java 21+. Vulnerabilities & Security RisksNone. Jackson 2.17.2 is an actively maintained release with zero known CVEs or security advisories. JVM Command-Line FlagsNone required. Unlike legacy libraries, Jackson 2.17.2 adheres strictly to JPMS encapsulation and reflection rules out of the box. Recommended StrategyWill upgrading require rewriting code calls?NO. All standard annotations (@JsonProperty, @JsonIgnore, @JsonInclude, @JsonCreator, etc.) remain 100% backward compatible. Moving your runtime to Java 21 requires zero code or annotation edits. Best PracticesKeep version 2.17.2 as-is. Ensure related Jackson modules (jackson-core and jackson-databind) share version 2.17.2 or are aligned via the BOM: com.fasterxml.jackson:jackson-bom:2.17.2. Maven ConfigurationXML com.fasterxml.jackson.core jackson-annotations 2.17.2 Gradle ConfigurationGroovyimplementation 'com.fasterxml.jackson.core:jackson-annotations:2.17.2'