GHSA-4mq4-7rw3-vm5j
HIGHWasmer filesystem sandbox not enforced
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
wasmer-cliReal-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
Summary
As of Wasmer version v4.2.3, Wasm programs can access the filesystem outside of the sandbox.
Details
https://github.com/wasmerio/wasmer/issues/4267
PoC
A minimal Rust program:
fn main() {
let f = std::fs::OpenOptions::new()
.write(true)
.create_new(true)
.open("abc")
.unwrap();
}
This should be compiled with cargo build --target wasm32-wasi. The compiled program, when run with wasmer WITHOUT --dir, can still create a file in the working directory.
Impact
Service providers running untrusted Wasm code on Wasmer can unexpectedly expose the host filesystem.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | wasmer-cli | ≥ 3.0.0&&< 4.2.4 | 4.2.4 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for wasmer-cli. 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 wasmer-cli to 4.2.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4mq4-7rw3-vm5j 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-4mq4-7rw3-vm5j 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-4mq4-7rw3-vm5j. 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-4mq4-7rw3-vm5j in your dependencies?
O3 detects GHSA-4mq4-7rw3-vm5j 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.