Improper Control of Generation of Code ('Code Injection') Affecting vyper package, versions [0, 0.4.0)

vyper is a Pythonic Smart Contract Language for the EVM.

Affected versions of this package are vulnerable to Improper Control of Generation of Code ('Code Injection') due to the _build_create_IR function of the create_from_blueprint builtin not caching the args argument to the stack, leading to its potential evaluation multiple times instead of retrieving the value from the stack. This could allow an attacker to trigger unintended behavior by exploiting the double evaluation of args.

src1 = """
c: uint256
"""
deployer = """
created_address: public(address)
deployed: public(uint256)

@external
def get() -> Bytes[32]:
    self.deployed += 1
    return b''

@external
def create_(target: address):
    self.created_address = create_from_blueprint(target, raw_call(self, method_id("get()"), max_outsize=32), raw_args=True, code_offset=3)
"""

Factory = b.loads_partial(src1)
c = Factory.deploy_as_blueprint()

c2 = b.loads(deployer, b'')
c2.create_(c)
c2.deployed()

• GitHub Commit
• Vulnerable Code