Ruby's Bundler 4.0.18 Extends Cooldown to bundle lock and bundle cache
Brief
Bundler 4.
- 18 adds the opt-in --cooldown flag to bundle lock and bundle cache , closing gaps where the setting could not be applied.
Bundler 4.
- 18, released August 5, 2026 alongside RubyGems 4.
- 18, extends the cooldown feature to two more commands. The opt-in --cooldown flag now works with bundle lock and bundle cache , which previously resolved dependencies without accepting the flag. RubyGems lists the change under Bundler security in the release notes .
The cooldown feature is not new. It shipped in Bundler 4.
- 13 in June as a time-based filter that refuses to resolve to a gem version until it has been public for a set number of days. The 4.
- 18 change does not alter how cooldown works. It makes the flag available on commands that were left out of the first release.