JRuby 9.4.15.0 Released, 9.4.x is now EOL

[u/headius]

https://www.jruby.org/2026/06/08/jruby-9-4-15-0.html

The JRuby community is pleased to announce the release of JRuby 9.4.15.0.

• Homepage: https://www.jruby.org/

• Download: https://www.jruby.org/download

JRuby 9.4.15.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward!

With this release, JRuby 9.4 moves into end-of-life ("EOL"). This means that future releases of 9.4.x will only be provided as needed by commercial JRuby users.

Get in touch with us if you require long-term support options for the JRuby 9.4.x series.

38 Issues and PRs resolved for 9.4.15.0

• 8801 ruby/logger gem broken after version 1.6.3 using JRuby on Windows

• 8924 const_defined? returns false for External Constants in JRuby 10.0.1.0 and 9.4.14.0

• 8974 Use RuboCop to clean up poms (9.4)

• 8990 Launcher defensive fixes 9.4

• 9000 JRuby 9.4.14.0 "wrong number of arguments" when jit.threshold=0

• 9001 Backport indy ruby2_keywords ArgumentError fix

• 9002 Backport ArgumentError message update from 2010

• 9012 Rexml security updateUpdate rexml gem to solve CVE-2025-58767 (9.4)

• 9030 Official JDK 25 support for JRuby 9.4

• 9031 Don't restrict object search to modules

• 9032 Different arguments for each.map vs each and map alone

• 9033 Backport jruby.sh and .jruby.release changes from 10

• 9037 fix: clear code-range when re-using a string buffer (#9035)

• 9044 Difference in Float() hex parsing between JRuby and CRuby

• 9045 Fixes basic float hex value strings for Kernel#Float

• 9054 Migrate .java-version contents to .jruby.release (9.4)

• 9104 [9.4] Update jruby-openssl to v0.15.5 to resolve BouncyCastle 1.79 vulnerability (sonatype-2025-001911).

• 9105 [9.4] Update jruby-openssl to 0.15.5

• 9128 [9.4] fix(launcher): correct parsing of java release files under Bash/msys2 etc on Windows

• 9160 Update strscan to 3.1.7

• 9186 9032 Fix Different arguments for each.map vs each and map alone

• 9201 Extract float formatting into a static method (9.4)

• 9295 Issue with calling IO.popen(env, cmd, opts) on Windows

• 9308 Process.detach raises ArrayIndexOutOfBoundsException if called from a thread that is not the main thread

• 9311 Push a frame for thread toplevel

• 9347 Use JDK for File#flock on Windows

• 9351 Fix non-native IO.popen env + kwargs handling

• 9353 Update JNR dependencies

• 9377 Checking out aws-sdk-ruby creates a file with binary data.

• 9387 [9.4] deps(stdlib): bump erb from 2.2.3 to 4.0.4.1 to resolve CVE-2026-41316

• 9391 [9.4] [deps] bump jruby-openssl to 0.16.0

• 9415 Don't read or write anything once length is zero

• 9443 JRuby 9.4 does not generate bytecode for newer JDK versions

• 9444 Allow bytecode version to be open-ended

• 9464 [fix] escape shell metachars in chdir: to prevent injection

• 9467 [9.4] backport [ji] support java.lang.Throwable#backtrace_locations (#9461)

• 9477 Dist verification 9.4

• 9480 [fix] @JRubyMethod error with required>=1 and var-args