GHSA-3whq-64q2-qfj6
MEDIUMvyper performs double eval of raw_args in create_from_blueprint
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
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Description
Summary
Using the create_from_blueprint builtin can result in a double eval vulnerability when raw_args=True and the args argument has side-effects.
A contract search was performed and no vulnerable contracts were found in production. In particular, the raw_args variant of create_from_blueprint was not found to be used in production.
Details
It can be seen that the _build_create_IR function of the create_from_blueprint builtin doesn't cache the mentioned args argument to the stack: https://github.com/vyperlang/vyper/blob/cedf7087e68e67c7bfbd47ae95dcb16b81ad2e02/vyper/builtins/functions.py#L1847
As such, it can be evaluated multiple times (instead of retrieving the value from the stack).
PoC
The vulnerability is demonstrated in the following boa test:
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()
The output of c2.deployed() is 2 although create_ was called only once and the value was initialized to 0.
Patches
Patched in https://github.com/vyperlang/vyper/pull/3976.
Impact
No vulnerable production contracts were found. Additionally, double evaluation of side-effects should be easily discoverable in client tests. As such, the impact is low.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | vyper | all versions | 0.4.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for vyper. 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 vyper to 0.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3whq-64q2-qfj6 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-3whq-64q2-qfj6 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-3whq-64q2-qfj6. 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-3whq-64q2-qfj6 in your dependencies?
O3 detects GHSA-3whq-64q2-qfj6 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.