CVE-2023-40015: Vyper is a Pythonic Smart Contract Language. For the following (probably non-exhaustive) list of expressions, the compiler evaluates the arguments fro...

Description

Vyper is a Pythonic Smart Contract Language. For the following (probably non-exhaustive) list of expressions, the compiler evaluates the arguments from right to left instead of left to right. `unsafe_add, unsafe_sub, unsafe_mul, unsafe_div, pow_mod256, |, &, ^ (bitwise operators), bitwise_or (deprecated), bitwise_and (deprecated), bitwise_xor (deprecated), raw_call, <, >, <=, >=, ==, !=, in, not in (when lhs and rhs are enums)`. This behaviour becomes a problem when the evaluation of one of the arguments produces side effects that other arguments depend on. The following expressions can produce side-effect: state modifying external call , state modifying internal call, `raw_call`, `pop()` when used on a Dynamic Array stored in the storage, `create_minimal_proxy_to`, `create_copy_of`, `create_from_blueprint`. This issue has not yet been patched. Users are advised to make sure that the arguments of the expression do not produce side effects or, if one does, that no other argument is dependent on those side effects.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS Probability

0.42%

33.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-670

Affected Software

Vendor	Product	Versions
Vyperlang	Vyper	<= 0.3.9

References

https://github.com/vyperlang/vyper/security/advisories/GHSA-g2xh-c426-v8mfExploit, Third Party Advisory
https://github.com/vyperlang/vyper/security/advisories/GHSA-g2xh-c426-v8mfExploit, Third Party Advisory

Timeline

Published: Sep 4, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-40015?

Vyper is a Pythonic Smart Contract Language. For the following (probably non-exhaustive) list of expressions, the compiler evaluates the arguments from right to left instead of left to right. `unsafe_add, unsafe_sub, unsafe_mul, unsafe_div, pow_mod256, |, &, ^ (bitwise operators), bitwise_or (deprecated), bitwise_and (deprecated), bitwise_xor (deprecated), raw_call, <, >, <=, >=, ==, !=, in, not in (when lhs and rhs are enums)`. This behaviour becomes a problem when the evaluation of one of the arguments produces side effects that other arguments depend on. The following expressions can produce side-effect: state modifying external call , state modifying internal call, `raw_call`, `pop()` when used on a Dynamic Array stored in the storage, `create_minimal_proxy_to`, `create_copy_of`, `create_from_blueprint`. This issue has not yet been patched. Users are advised to make sure that the arguments of the expression do not produce side effects or, if one does, that no other argument is dependent on those side effects.

How severe is CVE-2023-40015?

CVE-2023-40015 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.42% probability of exploitation in the next 30 days.

How do I fix CVE-2023-40015?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.