GHSA-cmr8-5w4c-44v8 is a high-severity (CVSS 7.5) CWE-335 vulnerability in @fastly/js-compute. O3 Security confirms whether GHSA-cmr8-5w4c-44v8 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Fastly Compute@Edge JS Runtime has fixed random number seed during compilation
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.
@fastly/js-computenpmDescription
Impact
Math.random and crypto.getRandomValues methods failed to use sufficiently random values. The initial value to seed the CSPRNG (cryptographically secure pseudorandom number generator) was baked-in to the final WebAssembly module meaning the sequence of numbers generated was predictable for that specific WebAssembly module. An attacker with access to that same WebAssembly module that calls the affected methods could use the fixed seed to predict random numbers generated by these functions. This information could be used to bypass cryptographic security controls, for example to disclose sensitive data encrypted by functions that use these generators.
Patches
The problem has been fixed in version 0.5.3.
Corrected Math.random and crypto.getRandomValues methods to always use sufficiently random values. The previous versions would use a CSPRNG (cryptographically secure pseudorandom number generator) which we would seed with a random value. However, due to our use of Wizer, the initial value to seed the CSPRNG was baked-in to the final WebAssembly module meaning the sequence of numbers generated was predictable for that specific WebAssembly module. The new implementations of both Math.random and crypto.getRandomValues do not use a CSPRNG and instead pull random values from WASI (WebAssembly System Interface) libc’s random_get function, which is always a sufficiently random value.
Workarounds
There are no workarounds, you must upgrade to version 0.5.3 or later.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @fastly/js-compute | ≥ 0.4.0&&< 0.5.3 | 0.5.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @fastly/js-compute. 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 @fastly/js-compute to 0.5.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cmr8-5w4c-44v8 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-cmr8-5w4c-44v8 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-cmr8-5w4c-44v8. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-cmr8-5w4c-44v8 in your dependencies?
O3 detects GHSA-cmr8-5w4c-44v8 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.