CVE-2024-47889: Possible ReDoS vulnerability in block_format in Action Mailer

There is a possible ReDoS vulnerability in the block_format helper in Action Mailer. This vulnerability has been assigned the CVE identifier CVE-2024-47889.

Impact

Carefully crafted text can cause the block_format helper to take an unexpected amount of time, possibly resulting in a DoS vulnerability. All users running an affected release should either upgrade or apply the relevant patch immediately.

Ruby 3.2 has mitigations for this problem, so Rails applications using Ruby 3.2 or newer are unaffected. Rails 8.0.0.beta1 requires Ruby 3.2 or greater so is unaffected.

Releases

The fixed releases are available at the normal locations.

Workarounds

Users can avoid calling the block_format helper or upgrade to Ruby 3.2

Credits

Thanks to yuki_osaki for the report!