How severe is CVE-2023-42460?

CVE-2023-42460 has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2023-42460?

CVE-2023-42460 affects the following packages: vyper (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2023-42460?

Update vyper to 0.3.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-42460 is resolved across your whole dependency graph.

How do I detect CVE-2023-42460 in my PyPI dependencies?

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.

How do I mitigate CVE-2023-42460 if there is no patch (or I can't update yet)?

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.

Is CVE-2023-42460 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2023-42460, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2023-42460?

CVE-2023-42460 has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 52th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2023-42460?

CVE-2023-42460 is classified as CWE-682 (CWE-682). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2023-42460 published, and has it been updated?

CVE-2023-42460 was published on September 26, 2023 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

MEDIUM severity

CVE-2023-42460 — vyper

MEDIUMFix: vyperlang/vyper#3626

CVE-2023-42460 is a medium-severity (CVSS 5.3) CWE-682 vulnerability in vyper. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for vyper — see the affected versions and patch details below.

_abi_decode input not validated in complex expressions in Vyper

Also known asGHSA-cx2q-hfxr-rj97PYSEC-2023-191

Published

Sep 26, 2023

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2023-42460.

EPSS Exploitation Probability

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs52th percentile — riskier than 52% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐍vyper

Real-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

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`vyper`	≥ 0.3.4&&< 0.3.10	0.3.10`pip install --upgrade 'vyper==0.3.10'`

Affected Products

1 product · 1 configurations

Application

vypervyperlang

≥ 0.3.4 && < 0.3.10

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Vyper is a Pythonic Smart Contract Language for the EVM. The `_abi_decod…

github.comNVDSep 2023

Detection & mitigation playbook

Open-source dependency

Detect
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 0.3.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-42460 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.

Frequently Asked Questions

### Impact `_abi_decode()` does not validate input when it is nested in an expression. the following example gets correctly validated (bounds checked): ```vyper x: int128 = _abi_decode(slice(msg.data, 4, 32), int128) ``` however, the following example is not bounds checked ```vyper @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