GHSA-cx2q-hfxr-rj97
MEDIUMVyper's `_abi_decode` input not validated in complex expressions
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
_abi_decode() does not validate input when it is nested in an expression. the following example gets correctly validated (bounds checked):
x: int128 = _abi_decode(slice(msg.data, 4, 32), int128)
however, the following example is not bounds checked
@external
def abi_decode(x: uint256) -> uint256:
a: uint256 = convert(_abi_decode(slice(msg.data, 4, 32), (uint8)), uint256) + 1
return a # abi_decode(256) returns: 257
the issue can be triggered by constructing an example where the output of _abi_decode is not internally passed to make_setter (an internal codegen routine) or other input validating routine.
Patches
https://github.com/vyperlang/vyper/pull/3626
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 | ≥ 0.3.4&&< 0.3.10 | 0.3.10 |
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 0.3.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cx2q-hfxr-rj97 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-cx2q-hfxr-rj97 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-cx2q-hfxr-rj97. 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-cx2q-hfxr-rj97 in your dependencies?
O3 detects GHSA-cx2q-hfxr-rj97 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.