CVE-2024-27456 — rack-cors
CRITICALCVE-2024-27456 is a critical-severity (CVSS 9.1) Information Exposure vulnerability in rack-cors. A fix is available for rack-cors — see the affected versions and patch details below.
Rack CORS Middleware has Insecure File Permissions
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-2024-27456.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
rack-corsReal-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
rack-cors (aka Rack CORS Middleware) 2.0.1 has 0666 permissions for the .rb files.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rack-cors | ≥ 2.0.1&&< 2.0.2 | 2.0.2bundle update rack-cors --conservative |
Affected Products
rack cors middlewarerylabsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rack-cors, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rack-cors to 2.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-27456 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.
Frequently Asked Questions
Is CVE-2024-27456 in your dependencies?
Find it across RubyGems, including transitive dependencies.