CVE-2021-23363 is a high-severity (CVSS 8.8) OS Command Injection vulnerability in kill-by-port. 1 public exploit reference exists, so weaponization risk is real. A fix is available for kill-by-port — see the affected versions and patch details below.
Arbitrary code execution in kill-by-port
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-23363 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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.
kill-by-portnpmDescription
This affects the package kill-by-port before 0.0.2. If (attacker-controlled) user input is given to the killByPort function, it is possible for an attacker to execute arbitrary commands. This is due to use of the child_process exec function without input sanitization.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | kill-by-port | all versions | 0.0.2npm install kill-by-port@0.0.2 |
Affected Products
kill-by-portkill-by-port_projectResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for kill-by-port, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update kill-by-port to 0.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-23363 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Frequently Asked Questions
Is CVE-2021-23363 in your dependencies?
Find it across npm, including transitive dependencies.