GHSA-2pgj-5cv2-6xxw
FuelVM is vulnerable to heap memory allocation re-use bug
Blast Radius
fuel-vm🦀fuel-vmReal-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
Impact
A memory safety vulnerability was present in the Fuel Virtual Machine (FuelVM), where memory reads could bypass expected access controls. Specifically, when a smart contract performed a mload (or other opcodes which access memory) on memory that had been deallocated using ret, it was still able to access the old memory contents. This occurred because the memory region was not zeroed out or otherwise marked as invalid. As a result, smart contracts could potentially read sensitive data left over from other contracts if the same memory was reallocated, violating isolation guarantees between contracts and enabling unintended data leakage.
All users running affected versions of FuelVM that relied on strict memory isolation between smart contracts were impacted.
Patches
The vulnerability was patched by modifying the FuelVM to ensure that memory deallocated with ret was zeroed out or made inaccessible. The fix was included in FuelVM version v0.60.1 and back-ported to v0.59.3. This patch was released to the Fuel network on Friday, April 18th, 2025.
Workarounds
There were no reliable workarounds that fully mitigated the vulnerability. While developers could manually zero out sensitive memory regions before returning from a function, this approach was error-prone and could not be enforced at the VM level. Upgrading to a patched version remained the recommended course of action.
References
- Fix implemented in the FuelVM GitHub repository (https://github.com/FuelLabs/fuel-vm/pull/941)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | fuel-vm | all versions | 0.59.3 |
| 🦀crates.io | fuel-vm | ≥ 0.60.0&&< 0.60.1 | 0.60.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fuel-vm. 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 fuel-vm to 0.59.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2pgj-5cv2-6xxw 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-2pgj-5cv2-6xxw 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-2pgj-5cv2-6xxw. 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-2pgj-5cv2-6xxw in your dependencies?
O3 detects GHSA-2pgj-5cv2-6xxw 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.