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CVE-2020-37289medium6.3

Vyper before 0.3.1 Improper Input Validation of uint8 Interface Return Values

Impact

Vyper before 0.3.1 lacks input validation for uint8 interface return values, allowing malicious contracts to manipulate contract logic. Affected versions are before 0.3.1. The weakness is improper input validation.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Affected packages

This source has no supported package-version data for matching. You can read the advisory here, but this record alone cannot power a dependency check.

Affected products

Vendor version evidence. Product records are separate from automatic dependency matching.

vyperlang · VulnCheck

vyper

2 ranges
VulnCheck version evidence

Package identity

pkg:pypi/vyperExplore vyper →

Identity supplied by VulnCheck. Version matching requires compatible range evidence.

Compare with this publisher’s ranges. This does not inspect your installation.

affected

0 → before 0.3.1

python versions

unaffected

0.3.1

python versions

unknown

Other versions: unaffected

Original source description

Vyper before 0.3.1 lacks a uint8 type, allowing interface return values declared as uint8, such as ERC20.decimals(), to be stored in uint256 variables without bounds checking. Malicious contracts can return values greater than 255 to manipulate or bypass contract logic that relies on these values.

Inside the record

Evidence available

Package identity
Version evidence
Remediation guidance · not supplied
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2020-37289

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-20 ↗

Improper Input Validation

VulnCheck

Related →

Environment requirements

These conditions apply together as specified by the publisher. A matching product name alone does not establish exposure.

VulnCheck · platform conditions

Any condition may hold

Vulnerable product

cpe:2.3:a:vyperlang:vyper:*:*:*:*:*:*:*:*

Before: 0.3.1

Original applicability statements
[
  {
    "nodes": [
      {
        "operator": "OR",
        "negate": false,
        "cpeMatch": [
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:a:vyperlang:vyper:*:*:*:*:*:*:*:*",
            "versionEndExcluding": "0.3.1"
          }
        ]
      }
    ]
  }
]
Contributing organizations · 2
VulnCheck

Assigning organization

2026-10-21
CISA-ADP

Additional data publisher

2026-10-28

What changed

Follow changes
No substantive changes have been recorded here yet. History starts when cve.new observes a change after tracking is enabled; earlier edits are not reconstructed.

Large field values are marked as truncated previews. Original source snapshots remain retained.

References

2 sources
github.com/vyperlang/vyper/security/advisories/GHSA-mr6r-mvw4-736g
vendor-advisoryVulnCheck
www.vulncheck.com/advisories/vyper-before-0.3.1-improper-input-validation-of-uint8-interface-return-values
third-party-advisoryVulnCheck