GHSA-mjfq-3qr2-6g84 Cosmos EVM Allows Partial Precompile State Writes

Not scored Published

Attackers can exploit gas limits to partially execute precompiles, causing unauthorized fund transfers or halting validators via indeterministic execution.

Exploited in the wild
Not known
Login needed
Any signed-in user
Attackable
Over the internet
Victim action needed
Not needed
Fix
None listed

What is GHSA-mjfq-3qr2-6g84?

GHSA-mjfq-3qr2-6g84 is a vulnerability in github.com/cosmos/evm, published on 14 May 2025. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Impact

Setting lower EVM call gas allows users to partially execute precompiles and error at specific points in the precompile code without reverting the partially written state.

If executed on the distribution precompile when claiming funds, it could cause funds to be transferred to a user without resetting the claimable rewards to 0. The vulnerability could also be used to cause indeterministic execution by failing at other points in the code, halting validators.

Any evmOS or Cosmos EVM chain using precompiles is affected.

Patches

The vulnerability was patched by wrapping each precompile execution into an atomic function that reverts any partially committed state on error.

For chains using a different file structure, you must manually apply the diff:

In x/evm/statedb.go:

Add the following function:

func (s *StateDB) RevertMultiStore(cms storetypes.CacheMultiStore, events sdk.Events) {
	s.cacheCtx = s.cacheCtx.WithMultiStore(cms)
	s.writeCache = func() {
		// rollback the events to the ones
		// on the snapshot
		s.ctx.EventManager().EmitEvents(events)
		cms.Write()
	}
}

In x/evm/statedb/journal.go:

Replace the Revert function with the following:

func (pc precompileCallChange) Revert(s *StateDB) {
	// rollback multi store from cache ctx to the previous
	// state stored in the snapshot
	s.RevertMultiStore(pc.multiStore, pc.events)
}

In precompiles/common/precompile.go:

Change the function signature in HandleGasError to:

func HandleGasError(ctx sdk.Context, contract *vm.Contract, initialGas storetypes.Gas, err *error, stateDB *statedb.StateDB, snapshot snapshot) func() {
...
}

In the HandleGasError function, add the following line in the switch statement in the case storetypes.ErrorOutOfGas: case:

stateDB.RevertMultiStore(snapshot.MultiStore, snapshot.Events)

Add the following function:

// RunAtomic is used within the Run function of each Precompile implementation.
// It handles rolling back to the provided snapshot if an error is returned from the core precompile logic.
// Note: This is only required for stateful precompiles.
func (p Precompile) RunAtomic(s snapshot, stateDB *statedb.StateDB, fn func() ([]byte, error)) ([]byte, error) {
	bz, err := fn()
	if err != nil {
		// revert to snapshot on error
		stateDB.RevertMultiStore(s.MultiStore, s.Events)
	}
	return bz, err
}

All Precompiles:

Finally, in each precompile, locate the Run function, and wrap each switch statement and return values into p.RunAtomic. For example:

// Run executes the precompiled contract IBC transfer methods defined in the ABI.
func (p Precompile) Run(evm *vm.EVM, contract *vm.Contract, readOnly bool) (bz []byte, err error) {
	ctx, stateDB, snapshot, method, initialGas, args, err := p.RunSetup(evm, contract, readOnly, p.IsTransaction)
	if err != nil {
		return nil, err
	}

	// This handles any out of gas errors that may occur during the execution of a precompile tx or query.
	// It avoids panics and returns the out of gas error so the EVM can continue gracefully.
	defer cmn.HandleGasError(ctx, contract, initialGas, &err, stateDB, snapshot)()

        // === WRAP HERE ===
	return p.RunAtomic(snapshot, stateDB, func() ([]byte, error) {
		switch method.Name {
		// TODO Approval transactions => need cosmos-sdk v0.46 & ibc-go v6.2.0
		// Authorization Methods:
		case exampleCase:
			bz, err = p.example(ctx, evm.Origin, stateDB, method, args)
		default:
			return nil, fmt.Errorf(cmn.ErrUnknownMethod, method.Name)
		}

		if err != nil {
			return nil, err
		}

		cost := ctx.GasMeter().GasConsumed() - initialGas

		if !contract.UseGas(cost) {
			return nil, vm.ErrOutOfGas
		}

		if err := p.AddJournalEntries(stateDB, snapshot); err != nil {
			return nil, err
		}

		return bz, nil
	})
}

Workarounds

There are no workarounds for chains that make use of precompiles. A coordinated upgrade is necessary to patch the issue.

Testing

A test was introduced in the distribution precompile to ensure that partial state writes no longer occur when a lower gas amount is set.

Which versions are affected by GHSA-mjfq-3qr2-6g84?

3 open source packages ship an affected version, including github.com/cosmos/evm.

PackageAffectedFixed in
github.com/cosmos/evm GoAll versionsNone
github.com/cosmos/evm GoAll versionsNone
github.com/cosmos/evm GoAll versionsNone

How do I fix GHSA-mjfq-3qr2-6g84?

No fix has been published for GHSA-mjfq-3qr2-6g84 yet. Limit exposure of the affected software until one is available.

Is GHSA-mjfq-3qr2-6g84 being exploited?

There is no known exploitation of GHSA-mjfq-3qr2-6g84 in the wild and no public exploit code.

Sources

Also known as GO-2025-3684.

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