CVE-2024-39943 is a critical-severity (CVSS 9.9) OS Command Injection vulnerability in hfs. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for hfs — see the affected versions and patch details below.
rejetto HFS vulnerable to OS Command Execution by remote authenticated users
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-39943.
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
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.
hfsnpmDescription
rejetto HFS (aka HTTP File Server) 3 before 0.52.10 on Linux, UNIX, and macOS allows OS command execution by remote authenticated users (if they have Upload permissions). This occurs because a shell is used to execute df (i.e., with execSync instead of spawnSync in child_process in Node.js).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | hfs | all versions | 0.52.10npm install hfs@0.52.10 |
Affected Products
http file serverrejettoResearch 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 hfs, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update hfs to 0.52.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-39943 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-2024-39943 in your dependencies?
Find it across npm, including transitive dependencies.