CVE-2021-32740
HIGHCVE-2021-32740 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in addressable. O3 Security confirms whether CVE-2021-32740 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Regular Expression Denial of Service in Addressable templates
Blast Radius
addressableReal-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
Addressable is an alternative implementation to the URI implementation that is part of Ruby's standard library. An uncontrolled resource consumption vulnerability exists after version 2.3.0 through version 2.7.0. Within the URI template implementation in Addressable, a maliciously crafted template may result in uncontrolled resource consumption, leading to denial of service when matched against a URI. In typical usage, templates would not normally be read from untrusted user input, but nonetheless, no previous security advisory for Addressable has cautioned against doing this. Users of the parsing capabilities in Addressable but not the URI template capabilities are unaffected. The vulnerability is patched in version 2.8.0. As a workaround, only create Template objects from trusted sources that have been validated not to produce catastrophic backtracking.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | addressable | ≥ 2.3.0&&< 2.8.0 | 2.8.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for addressable. 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 addressable to 2.8.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32740 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-2021-32740 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-2021-32740. 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-2021-32740 in your dependencies?
O3 detects CVE-2021-32740 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.