CVE-2020-37288: Vyper 0.1.0b10 before 0.2.3 Invalid Jump Destination via Return in Nested Loops

Q: Which contracts are realistically exposed to this issue?

Contracts compiled with Vyper from 0.1.0b10 before 0.2.3 are affected only if they contain a return statement inside a for loop within an internal function that is invoked through two or more layers of internal calls.

Q: What must happen for the vulnerability to cause impact?

The affected internal-call path must be executed so that the incorrectly generated return code reaches an invalid jump destination and causes a stack underflow. The resulting behavior is an unnecessary revert, which may enable denial of service in limited circumstances for public contracts.

Q: Is a contract affected simply because it was compiled with an affected Vyper version?

No. In addition to using a version from 0.1.0b10 before 0.2.3, the contract must use the specific combination of a return inside a for loop and an internal function call chain at least two calls deep.

Published Oct 21, 2026

Updated

Vyper from 0.1.0b10 before 0.2.3 generates incorrect code for a return statement inside a for loop in an internal function called two or more internal calls deep, producing an invalid jump destination (stack underflow). Affected contracts revert such calls unnecessarily, which in limited circumstances could enable denial of service against public contracts.

Affected Software

1 affected component

Vyper Vyper>=0.1.0b10<0.2.3

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade Vyper to a version that resolves this vulnerability.
Fixed in 0.2.3

Event History

Oct 21, 2026

CVE Published

via MITRE·12:36 AM

Data Sourced

via MITRE·12:36 AM

DescriptionSeverityWeakness

Frequently Asked Questions

Which contracts are realistically exposed to this issue?

Contracts compiled with Vyper from 0.1.0b10 before 0.2.3 are affected only if they contain a return statement inside a for loop within an internal function that is invoked through two or more layers of internal calls.

What must happen for the vulnerability to cause impact?

The affected internal-call path must be executed so that the incorrectly generated return code reaches an invalid jump destination and causes a stack underflow. The resulting behavior is an unnecessary revert, which may enable denial of service in limited circumstances for public contracts.

Is a contract affected simply because it was compiled with an affected Vyper version?

No. In addition to using a version from 0.1.0b10 before 0.2.3, the contract must use the specific combination of a return inside a for loop and an internal function call chain at least two calls deep.

CVE-2020-37288: Vyper 0.1.0b10 before 0.2.3 Invalid Jump Destination via Return in Nested Loops

Affected Software

Remediation

Event History

Frequently Asked Questions

Which contracts are realistically exposed to this issue?

What must happen for the vulnerability to cause impact?

Is a contract affected simply because it was compiled with an affected Vyper version?

Company

Resources

Contact

Frequently Asked Questions

Which contracts are realistically exposed to this issue?

What must happen for the vulnerability to cause impact?

Is a contract affected simply because it was compiled with an affected Vyper version?