GHSA-2v37-7h3g-55p8 is a medium-severity (CVSS 5.9) CWE-835 vulnerability in nanoid. O3 Security confirms whether GHSA-2v37-7h3g-55p8 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
nanoid: custom generators can loop indefinitely when size is zero
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-2v37-7h3g-55p8.
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
GHSA-2v37-7h3g-55p8 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 372,613 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.
nanoidnpmDescription
nanoid (Nano ID) before 5.1.6 contains an infinite loop in the customAlphabet and customRandom functions. When these functions are configured with a size of 0, the internal generation loop never satisfies its exit condition and spins indefinitely, hanging the calling thread. An application that passes an unvalidated, attacker-controlled size of 0 to these functions is exposed to a denial-of-service condition.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | nanoid | all versions | 3.3.18 |
| 📦npm | nanoid | ≥ 4.0.0&&< 5.1.6 | 5.1.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nanoid. 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 nanoid to 3.3.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2v37-7h3g-55p8 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 GHSA-2v37-7h3g-55p8 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 GHSA-2v37-7h3g-55p8. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
An algorithmic denial of service flaw was found in the `nanoid` library. When calling `customAlphabet` or `customRandom` with a `size` parameter of `0`, the internal generation loop fails to meet its termination condition. In Node.js or browser execution contexts, an attacker who supplies an unvalidated, zero-value…
Frequently Asked Questions
Is GHSA-2v37-7h3g-55p8 in your dependencies?
O3 detects GHSA-2v37-7h3g-55p8 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.