GHSA-2pgj-5cv2-6xxw FuelVM is vulnerable to heap memory allocation re-use bug
Attackers can read sensitive data from other smart contracts due to improper memory deallocation in FuelVM, violating isolation guarantees.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-2pgj-5cv2-6xxw?
GHSA-2pgj-5cv2-6xxw is a vulnerability in fuel-vm, published on 8 Oct 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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)
Which versions are affected by GHSA-2pgj-5cv2-6xxw?
4 open source packages ship an affected version, including fuel-vm.
| Package | Affected | Fixed in |
|---|---|---|
fuel-vm crates.io | All versions | 0.59.3 |
fuel-vm crates.io | All versions | 0.59.3 |
fuel-vm crates.io | From 0.60.0 | 0.60.1 |
fuel-vm crates.io | From 0.60.0 | 0.60.1 |
How do I fix GHSA-2pgj-5cv2-6xxw?
Upgrade fuel-vm to a fixed version for your release line: 0.59.3 or 0.60.1.
Is GHSA-2pgj-5cv2-6xxw being exploited?
There is no known exploitation of GHSA-2pgj-5cv2-6xxw in the wild and no public exploit code.