GHSA-4mq4-7rw3-vm5j is a high-severity (CVSS 8.4) CWE-284 vulnerability in wasmer-cli. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for wasmer-cli — see the affected versions and patch details below.
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for GHSA-4mq4-7rw3-vm5j.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
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 | 4.2.4cargo update -p wasmer-cli --precise 4.2.4 |
Affected Products
wasmerwasmerResearch 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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is GHSA-4mq4-7rw3-vm5j in your dependencies?
Find it across crates.io, including transitive dependencies.