CVE-2021-48020 PUBLISHED

Vyper before 0.3.0 Memory Corruption via Internal Function Calls in Arrays

Assigner: VulnCheck
Reserved: 20.10.2026 Published: 21.10.2026 Updated: 21.10.2026

Vyper from 0.1.0b4 before 0.3.0 contains a memory corruption vulnerability caused by an incorrect stack tip pointer when internal function calls are performed inside arrays. Contracts placing internal calls in nested array elements, external call arguments, struct literals, or raw_log topics can have memory corrupted, producing incorrect contract behavior.

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N
CVSS Score: 8.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	High	Integrity	None
Attack Requirements	Present	Availability	Low	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L
CVSS Score: 6.5

Attack Vector	Network	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	High
User Interaction	None	Availability Impact	Low

CVSS 3.1

Product Status

Vendor	vyperlang
Product	vyper
Versions	Default: unaffected affected from 0.1.0b4 to 0.3.0 (excl.) Version 0.3.0 is unaffected

References

Problem Types

Out-of-bounds Write CWE