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Fencer Vulns
medium 5.3

CVE-2023-42460 json

_abi_decode input not validated in complex expressions in Vyper

published 2023-09-26 3 y ago modified 2026-06-17 4 mo ago also GHSA-cx2q-hfxr-rj97 , PYSEC-2023-191 , EUVD-2023-0268

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits
0
none known

Summary

Vyper is a Pythonic Smart Contract Language for the EVM. The `_abi_decode()` function does not validate input when it is nested in an expression. Uses of `_abi_decode()` can be constructed which allow for bounds checking to be bypassed resulting in incorrect results. This issue has not yet been fixed, but a fix is expected in release `0.3.10`. Users are advised to reference pull request #3626.

Patch / fix

  • pypi vyper 0.3.10
  • vyperlang vyper 0.3.10

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.67% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/vyperlang/vyper/security/advisories/GHSA-cx2q-hfxr-rj97 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
pypi vyper
>=0.3.4, <0.3.10
0.3.10

Affected products

  • vyperlang vyper

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.