CVE-2024-24564 is a low-severity (CVSS 3.7) Out-of-bounds Read vulnerability in vyper. 1 public exploit reference exists, so weaponization risk is real. A fix is available for vyper — see the affected versions and patch details below.
Vyper extract32 can ready dirty memory
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-24564.
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.
How urgent is this, really
CVE-2024-24564 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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
Summary
When using the built-in extract32(b, start), if the start index provided has for side effect to update b, the byte array to extract 32 bytes from, it could be that some dirty memory is read and returned by extract32.
As of v0.4.0 (specifically, commit https://github.com/vyperlang/vyper/commit/3d9c537142fb99b2672f21e2057f5f202cde194f), the compiler will panic instead of generating bytecode.
Details
Before evaluating start, the function Extract32.build_IR caches only:
- The pointer in memory/storage to
b: https://github.com/vyperlang/vyper/blob/10564dcc37756f3d3684b7a91fd8f4325a38c4d8/vyper/builtins/functions.py#L916-L918 - The length of
b: https://github.com/vyperlang/vyper/blob/10564dcc37756f3d3684b7a91fd8f4325a38c4d8/vyper/builtins/functions.py#L920-L922
but do not cache the actual content of b. This means that if the evaluation of start changes b's content and length, an outdated length will be used with the new content when extracting 32 bytes from b.
PoC
Calling the function foo of the following contract returns b'uuuuuuuuuuuuuuuuuuuuuuuuuuu\x00\x00789' meaning that extract32 accessed some dirty memory.
var:Bytes[96]
@internal
def bar() -> uint256:
self.var = b'uuuuuuuuuuuuuuuuuuuuuuuuuuuuuu'
self.var = b''
return 3
@external
def foo() -> bytes32:
self.var = b'abcdefghijklmnopqrstuvwxyz123456789'
return extract32(self.var, self.bar(), output_type=bytes32)
# returns b'uuuuuuuuuuuuuuuuuuuuuuuuuuu\x00\x00789'
Impact
For contracts that are affected, it means that calling extract32 returns dirty memory bytes instead of some expected output.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | vyper | all versions | 0.4.0pip install --upgrade 'vyper==0.4.0' |
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update vyper to 0.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-24564 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-24564 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-24564. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2024-24564 in your dependencies?
O3 Security finds CVE-2024-24564 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.