Improper Control of Generation of Code ('Code Injection') Affecting vyper package, versions [0, 0.4.0)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-PYTHON-VYPER-6674052
- published26 Apr 2024
- disclosed25 Apr 2024
- creditUnknown
Introduced: 25 Apr 2024
CVE-2024-32647 (opens in a new tab)How to fix?
Upgrade vyper to version 0.4.0 or higher.
Overview
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.
PoC
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()