Today we were informed of a low-severity vulnerability in the bcrypt-ruby gem. We worked with the maintainers to arrange a fix. Upgrading is recommended. CVE-2026-33306: Integer Overflow Causes Zero Key-Strengthening Iterations at Cost=31 on JRuby github.com/bcrypt-ruby/...

JRuby 10.0.4.0 is released! A month after 10.0.3.0, we've addressed lots of one-off issues, a few memory and thread-safety fixes, and general compatibility and stabilization work. Enjoy! www.jruby.org/2026/03/04/j...

JRuby 10.0.3.0 is released! Over 80 issues and pull requests and 13 external contributors combined to help further stabilize our 10.0 series! There's lots of compatibility fixes, a few performance enhancements, and a number of library updates. Upgrade is recommended! www.jruby.org/2026/02/02/j...

New post: Warbled Sidekiq: Zero-install Executable for JVM In my previous post, I showed how to use Warbler to package a simple tool as an executable jar. This post will demonstrate how to “warble” a larger project: the Sidekiq background job server! buff.ly/ZEasNiu

New post: "Packaging Ruby Apps with Warbler: Executable JAR Files" Warbler is the JRuby ecosystem’s tool for packaging up Ruby apps with all dependencies in a single deployable file. We’ve just released an update, so let’s use Warbler to create all-in-one packaged Ruby apps! buff.ly/ZdXcCop

Warbler 2.1.0 has been released! Warbler allows you to package JRuby applications (with obfuscation of code) as a single binary, either a .jar file you can run directly or a .war file you can deploy to any Java application server. Blog post coming! rubygems.org/gems/warbler...

We have published Docker images for JRuby 9.4 and JRuby 10 on JDK 25! The -dev images are also updated to latest commits. Give them a try and let us know if there's any issues!

At the end of my post on JRuby and JDK 25 startup time features, I teased a bit of the unreleased improvements from Project Leyden. It turns out the latest commits improve startup time even more, so it seems worth posting a quick follow-up! www.reddit.com/r/ruby/comme...

New post: JRuby and JDK 25: Startup Time with AOTCache Let's take a look at JRuby's startup time journey, all the way up to using JDK 25's AOTCache and Project Leyden features coming to a JDK near you soon. blog.headius.com/2025/09/jrub...

JRuby 9.4.14.0 is released! We've updated a bunch of the standard library (including "cgi" to fix a couple of CVEs), fixed a few memory leaks and a bunch of compatibility issues, and generally stabilized things. Upgrading is recommended! www.jruby.org/2025/08/28/j...

JRuby 10.0.2.0 is released! This is a small release to fix an ArgumentError regression in JRuby 10.0.1.0 plus a few other small fixes. Recommended upgrade for all, but let us know if you run into any issues! www.jruby.org/2025/08/07/j...

We have just released JRuby 10.0.1.0, our first update to JRuby 10! There's dozens of patches including full support (finally) for Zeitwerk and a bunch of Ruby 3.4 language fixes. Upgrade today and let us know how it goes! www.jruby.org/2025/07/17/j...

We have released jruby-maven-plugins 3.0.6, which updates JRuby to 9.4.13.0 along with several other improvements. But more exciting: Warbler is BACK! We've updated it for latest JRuby and dependencies and it's running green in CI. Time for feature requests! github.com/jruby/warble...

FYI: now that Ubuntu 20.04 is EOL, future releases of the JRuby Docker image will be based on Ubuntu 22.04. This will take effect with releases 9.4.14.0 and 10.0.1.0, whenever they happen. See github.com/docker-libra...

JRuby 9.4.13.0 is released! We have fixed several user issues, including a slow leak in Java interface implementation, a possible deadlock between JIT and main threads, and backported launcher improvements from JRuby 10! www.jruby.org/2025/06/10/j...

this week on the unikernel application spotlight we check out @jrubyproject.bsky.social www.youtube.com/watch?v=72wl... - real threads && jvm interop - congrats on 10.x release and 24 yrs! @headius.bsky.social

Security advisory: We have released jruby-openssl gem 0.15.4, jruby 10.0.0.1, and jruby 9.4.12.1 to address CVE-2025-46551, disabled hostname verification by default. We recommend that all users upgrade! www.cve.org/CVERecord?id... www.jruby.org/2025/05/07/j... www.jruby.org/2025/05/07/j...

Seems like a few folks didn't think my 2D bar chart was "beautiful", so let's kick it up a notch with 3D, SVG, and PDF generation using the same JFreeChart family of libraries! blog.headius.com/2025/05/3d-c...

It's finally here! JRuby 10 has been released with support for Ruby 3.4 (including 3.2 and 3.3 updates as well). Minimum Java version has been bumped up to Java 21, allowing us to support modern JVM features. Check out the release notes and start migrating today! www.jruby.org/2025/04/14/j...

It's almost time! I've just published my first post on JRuby 10, "Part 1: What's New". More posts will follow in the coming weeks, but JRuby 10 itself should be generally available before my RubyKaigi talk next week!

We have released jruby-launcher 2.0! This version eliminates the old C++ code in favor of two options: * On Unix systems, the launcher will exec the already-present jruby.sh script. * On Windows, we have a new Rust-based exe coming soon. Let us know if you have any issues:

JRuby 10 HEAD builds are now live in GitHub Actions setup-ruby and for any local Ruby installers that depend on jruby-dev-builder's jruby-head packages! Fingers crossed it doesn't cause too many problems, but let us know right away if something goes awry!

I just took pdf-reader for a spin on v10-SNAPSHOT, all green first try github.com/yob/pdf-read...

Calling all Rubyists! We are looking for help verifying third-party libraries on JRuby 10! I've opened an issue to track that process, and provided links to snapshot JRuby builds you can use to verify your own code. Please help us verify JRuby 10!

It's almost time! JRuby 10 is approaching release, and toward that end we will be switching JRuby master from the 9.4 line to the 10.0 line this week. The "jruby-head" build from GHA "setup-ruby" action will remain 9.4 for now, but it's time for you to start testing with JRuby 10!

New post: Boosting JRuby Startup with AppCDS and AOT caching https://buff.ly/4jUEKJc

JRuby 9.4.12.0 has been released with two important fixes: a thread-safety patch for recent Class#subclasses logic and an update for jar-dependencies to fix issues parsing Maven output on Java 9+. Let us know if you run into any new issues!

JRuby 9.4.11.0 is released with two critical fixes for bugs in 9.4.10.0 and a handful of stdlib upgrades. We recommend all users update to 9.4.11.0 and skip the 9.4.10.0 release. Let us know if you have issues!

We have released jar-dependencies 0.5.2, now that JRuby 9.4.10.0 can safely handle upgrading it independent of JRuby itself. This finally fixes issues sourcing jar dependencies from Maven in containerized environments (previously partially fixed by updating ruby-maven-libs).

JRuby 9.4.10.0 is released with over 50 issues and PRs! We've included some key targeted optimizations along with many user-facing bug fixes, library upgrades, and usability improvements. Upgrade today!

Psych 5.2.3 has been released. For JRuby users, this updates SnakeYAML-Engine to 2.9 and fixes an issue with numeric YAML aliases. ruby/psych: A libyaml wrapper for Ruby https://buff.ly/3Wq2QBr

We recently released an for the jar-dependencies gem, used to fetch jar dependencies from Maven Central. Unfortunately due to a bug (fixed in JRuby 9.4.10.0) we are considering pulling it temporarily. If anyone's got jar-dependencies 0.5.0 in their Gemfile.lock, we need to know!

JRuby is on Bluesky! Follow for release announcements, security notifications, and general JRuby fun!