Low severity · published Oct 21, 2026
CVE-2020-37289
Vyper before 0.3.1 Improper Input Validation of uint8 Interface Return Values
3.7
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 18% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
VY
vyper · vyperlang
before 0.3.1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-37289
CVE.org
https://www.cve.org/CVERecord?id=CVE-2020-37289
github.com
https://github.com/vyperlang/vyper/security/advisories/GHSA-mr6r-mvw4-736g
www.vulncheck.com
https://www.vulncheck.com/advisories/vyper-before-0.3.1-improper-input-validation-of-uint8-interface-return-values
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