CVE-2024-47889 — actionmailer
Fix: rails/rails@0e5694fCVE-2024-47889 is a CWE-1333 vulnerability in actionmailer. A fix is available for actionmailer — see the affected versions and patch details below.
Action Mailer has possible ReDoS vulnerability in block_format
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-47889.
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.
Real-World Exposure
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
Action Mailer is a framework for designing email service layers. Starting in version 3.0.0 and prior to versions 6.1.7.9, 7.0.8.5, 7.1.4.1, and 7.2.1.1, there is a possible ReDoS vulnerability in the block_format helper in Action Mailer. 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 to versions 6.1.7.9, 7.0.8.5, 7.1.4.1, or 7.2.1.1 or apply the relevant patch immediately. As a workaround, users can avoid calling the block_format helper or upgrade to Ruby 3.2. 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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | actionmailer | ≥ 3.0.0&&< 6.1.7.9 | 6.1.7.9bundle update actionmailer --conservative |
| 💎RubyGems | actionmailer | ≥ 7.0.0&&< 7.0.8.5 | 7.0.8.5bundle update actionmailer --conservative |
| 💎RubyGems | actionmailer | ≥ 7.1.0&&< 7.1.4.1 | 7.1.4.1bundle update actionmailer --conservative |
| 💎RubyGems | actionmailer | ≥ 7.2.0&&< 7.2.1.1 | 7.2.1.1bundle update actionmailer --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for actionmailer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update actionmailer to 6.1.7.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-47889 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-47889 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-47889. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Frequently Asked Questions
Is CVE-2024-47889 in your dependencies?
O3 Security finds CVE-2024-47889 across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.