CVE-2020-35926 is a medium-severity (CVSS 5.1) Insufficient Random Values vulnerability in nanorand. O3 Security confirms whether CVE-2020-35926 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Improper random number generation in nanorand
Real-World Exposure
nanorandReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
In versions of nanorand prior to 0.5.1, RandomGen implementations for standard unsigned integers could fail to properly generate numbers, due to using bit-shifting to truncate a 64-bit number, rather than just an as conversion. This often manifested as RNGs returning nothing but 0, including the cryptographically secure ChaCha random number generator.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | nanorand | all versions | 0.5.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nanorand. 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 nanorand to 0.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35926 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-2020-35926 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-2020-35926. 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-2020-35926 in your dependencies?
O3 detects CVE-2020-35926 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.