CVE-2016-2515 is a high-severity (CVSS 7.5) CWE-399 vulnerability in hawk. A fix is available for hawk — see the affected versions and patch details below.
Regular Expression Denial of Service in hawk
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.
How urgent is this, really
CVE-2016-2515 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
hawknpmDescription
Hawk before 3.1.3 and 4.x before 4.1.1 allow remote attackers to cause a denial of service (CPU consumption or partial outage) via a long (1) header or (2) URI that is matched against an improper regular expression.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | hawk | ≥ 4.0.0&&< 4.1.1 | 4.1.1npm install hawk@4.1.1 |
| 📦npm | hawk | all versions | 3.1.3npm install hawk@3.1.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hawk, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update hawk to 4.1.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-2515 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2016-2515 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2016-2515. 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-2016-2515 in your dependencies?
O3 Security finds CVE-2016-2515 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.