GHSA-ph9x-4vc9-m39g
HIGHVyper vulnerable to incorrect ordering of arguments for kwargs passed to internal calls
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
vyperReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Internal calls to internal functions with more than 1 default argument are compiled incorrectly. Depending on the number of arguments
provided in the call, the defaults are added not right-to-left, but left-to-right. If the types are incompatible,
typechecking is bypassed. In the bar() function in the following code, self.foo(13) is compiled to
self.foo(13,12) instead of self.foo(13,1337).
@internal
def foo(a:uint256 = 12, b:uint256 = 1337):
pass
@internal
def bar():
self.foo(13)
note that at the time of publication, the ability to pass kwargs to internal functions is an undocumented feature that does not seem to be widely used.
Patches
patched in c3e68c302aa6e1429946473769dd1232145822ac
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
References
Are there any links users can visit to find out more?
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | vyper | all versions | 0.3.8 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
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 0.3.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ph9x-4vc9-m39g 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-ph9x-4vc9-m39g 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-ph9x-4vc9-m39g. 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-ph9x-4vc9-m39g in your dependencies?
O3 detects GHSA-ph9x-4vc9-m39g across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.