GHSA-h47h-mwp9-c6q6
Possible ReDoS vulnerability in block_format in Action Mailer
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
actionmailer💎actionmailer💎actionmailer💎actionmailerReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
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!
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | actionmailer | ≥ 3.0.0&&< 6.1.7.9 | 6.1.7.9 |
| 💎RubyGems | actionmailer | ≥ 7.0.0&&< 7.0.8.5 | 7.0.8.5 |
| 💎RubyGems | actionmailer | ≥ 7.1.0&&< 7.1.4.1 | 7.1.4.1 |
| 💎RubyGems | actionmailer | ≥ 7.2.0&&< 7.2.1.1 | 7.2.1.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for actionmailer. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update actionmailer to 6.1.7.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-h47h-mwp9-c6q6 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-h47h-mwp9-c6q6 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-h47h-mwp9-c6q6. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-h47h-mwp9-c6q6 in your dependencies?
O3 detects GHSA-h47h-mwp9-c6q6 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.