CVE-2020-26149 is a high-severity (CVSS 7.5) CWE-522 vulnerability in nats. O3 Security confirms whether CVE-2020-26149 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Sensitive data exposure in NATS
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
natsnpmnats.wsnpmDescription
NATS nats.js before 2.0.0-209, nats.ws before 1.0.0-111, and nats.deno before 1.0.0-9 allow credential disclosure from a client to a server.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | nats | ≥ 2.0.0-201&&< 2.0.0-209 | 2.0.0-209 |
| 📦npm | nats.ws | ≥ 1.0.0-85&&< 1.0.0-111 | 1.0.0-111 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nats. 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 nats to 2.0.0-209 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-26149 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-2020-26149 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-2020-26149. 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-2020-26149 in your dependencies?
O3 detects CVE-2020-26149 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.