CVE-2023-27530
HIGHCVE-2023-27530 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in rack. O3 Security confirms whether CVE-2023-27530 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Rack has possible DoS Vulnerability in Multipart MIME parsing
Real-World Exposure
rack💎rack💎rack💎rackReal-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
A DoS vulnerability exists in Rack <v3.0.4.2, <v2.2.6.3, <v2.1.4.3 and <v2.0.9.3 within in the Multipart MIME parsing code in which could allow an attacker to craft requests that can be abuse to cause multipart parsing to take longer than expected.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rack | all versions | 2.0.9.3 |
| 💎RubyGems | rack | ≥ 2.1.0&&< 2.1.4.3 | 2.1.4.3 |
| 💎RubyGems | rack | ≥ 2.2.0&&< 2.2.6.3 | 2.2.6.3 |
| 💎RubyGems | rack | ≥ 3.0.0&&< 3.0.4.2 | 3.0.4.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rack. 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 rack to 2.0.9.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-27530 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 CVE-2023-27530 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 CVE-2023-27530. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-27530 in your dependencies?
O3 detects CVE-2023-27530 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.