CVE-2023-42460Network attack vector

Incorrect decoded values via unchecked nested ABI input

Published Sep 26, 2023 · Updated Sep 24, 2024

Incorrect calculation in Vyper 0.3.4 through 0.3.9 allows attackers to alter smart-contract results via crafted nested ABI decoding expressions. The _abi_decode() builtin skips bounds validation when its output is embedded in certain expressions because validation is deferred to make_setter, so out-of-range values can pass through conversions and arithmetic. An attacker must supply contract-call data that reaches such a compiler-generated decoder; the consequence is integrity-impacting incorrect contract behavior, with no confidentiality or availability impact reported.

CVSS severity7.5
High
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect calculation in Vyper 0.3.4 through 0.3.9 allows attackers to alter smart-contract results via crafted nested ABI decoding expressions. The _abi_decode() builtin skips bounds validation when its output is embedded in certain expressions because validation is deferred to make_setter, so out-of-range values can pass through conversions and arithmetic. An attacker must supply contract-call data that reaches such a compiler-generated decoder; the consequence is integrity-impacting incorrect contract behavior, with no confidentiality or availability impact reported.

The record

CVE
CVE-2023-42460
Published
Sep 26, 2023
Updated
Sep 24, 2024
Vendor
Vyper
Product
Vyper
Classifications
CWE-682
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 26, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 24, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.3.4, < 0.3.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Vyper · Vyperversion=>= 0.3.4, < 0.3.10

Published CVSS scores

5.3GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-682Incorrect Calculation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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