[!CAUTION] The Mastodon 4.2.x branch will not receive any update—including security fixes—after 2026-01-08. Please consider moving to a newer release as soon as possible.

[!WARNING] There is a known security issue in the version of ActiveRecord we use. While it is unlikely to affect you, it is worth being aware of, and we recommend updating to Mastodon v4.3 or newer if possible.

Changelog

Security

• Fix SSRF protection bypass (GHSA)

Fixed

• Fix mentions of domain-blocked users being processed (#37257 by @ClearlyClaire)

Upgrade notes

To get the code for v4.2.29, use git fetch && git checkout v4.2.29.

[!NOTE] As always, make sure you have backups of the database before performing any upgrades. If you are using docker-compose, this is how a backup command might look: docker exec mastodon_db_1 pg_dump -Fc -U postgres postgres > name_of_the_backup.dump

[!IMPORTANT] Since v4.2.10, Mastodon is now performing stricter checks to prevent client IP address spoofing. This means that if one of your reverse proxy is not on Mastodon’s local network, you will need to set TRUSTED_PROXY_IP accordingly, listing the IP address of every trusted reverse-proxy (including local network ones). See the documentation for more information.

Dependencies

The minimum supported Ruby version has been bumped from 3.0 to 3.1 in Mastodon v4.2.17. Otherwise, external dependencies have not changed since v4.2.4, the compatible PostgreSQL, Node, Elasticsearch and Redis versions are the same, that is:

• Ruby: 3.1 to 3.3
• PostgreSQL: 10 or newer
• Elasticsearch (recommended, for full-text search): 7.x (OpenSearch should also work)
• LibreTranslate (optional, for translations): 1.3.3 or newer
• Redis: 4 or newer
• Node: 16 or newer
• ImageMagick: 6.9.7-7 or newer

Update steps

[!TIP] The charlock_holmes gem may fail to build on some systems with recent versions of gcc. If you run into such an issue, try BUNDLE_BUILD__CHARLOCK_HOLMES="--with-cxxflags=-std=c++17" bundle install.

The following instructions are for updating from 4.2.28.

If you are upgrading directly from an earlier release, please carefully read the upgrade notes for the skipped releases as well, as they often require extra steps such as database migrations.

1. Restart all Mastodon processes