GHSA-mp3g-vpm9-9vqv
MEDIUM@fastly/js-compute has a use-after-free in some host call implementations
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.
Blast Radius
@fastly/js-computeReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Impact
The implementation of the following functions were determined to include a use-after-free bug:
FetchEvent.client.tlsCipherOpensslNameFetchEvent.client.tlsProtocolFetchEvent.client.tlsClientCertificateFetchEvent.client.tlsJA3MD5FetchEvent.client.tlsClientHelloCacheEntry.prototype.userMetadataof thefastly:cachesubsystemDevice.lookupof thefastly:devicesubsystem
This bug could allow for an unintended data leak if the result of the preceding functions were sent anywhere else, and often results in a Compute service crash causing an HTTP 500 error to be returned. As all requests to Compute are isolated from one another, the only data at risk is data present for a single request.
Patches
This bug has been fixed in version 3.16.0 of the @fastly/js-compute package.
Workarounds
There are no workarounds for this bug, any use of the affected functions introduces the possibility of a data leak or crash in guest code.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @fastly/js-compute | ≥ 3.0.0&&< 3.16.0 | 3.16.0 |
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 3.16.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mp3g-vpm9-9vqv 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-mp3g-vpm9-9vqv 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-mp3g-vpm9-9vqv. 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-mp3g-vpm9-9vqv in your dependencies?
O3 detects GHSA-mp3g-vpm9-9vqv across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.