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CVE-2023-40015

LOW
Published 2023-09-04T17:39:12.822Z
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CVSS Score

V3.1
3.7
/10
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Base Score Metrics
Exploitability: N/A Impact: N/A

EPSS Score

v2025.03.14
0.001
probability
of exploitation in the wild

There is a 0.1% chance that this vulnerability will be exploited in the wild within the next 30 days.

Updated: 2025-06-25
Exploit Probability
Percentile: 0.227
Higher than 22.7% of all CVEs

Attack Vector Metrics

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED

Impact Metrics

Confidentiality
NONE
Integrity
LOW
Availability
NONE

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.

Understanding This Vulnerability

This Common Vulnerabilities and Exposures (CVE) entry provides detailed information about a security vulnerability that has been publicly disclosed. CVEs are standardized identifiers assigned by MITRE Corporation to track and catalog security vulnerabilities across software and hardware products.

The severity rating (LOW) indicates the potential impact of this vulnerability based on the CVSS (Common Vulnerability Scoring System) framework. Higher severity ratings typically indicate vulnerabilities that could lead to more significant security breaches if exploited. Security teams should prioritize remediation efforts based on severity, exploit availability, and the EPSS (Exploit Prediction Scoring System) score, which predicts the likelihood of exploitation in the wild.

If this vulnerability affects products or systems in your infrastructure, we recommend reviewing the affected products section, checking for available patches or updates from vendors, and implementing recommended workarounds or solutions until a permanent fix is available. Organizations should also monitor security advisories and threat intelligence feeds for updates about active exploitation of this vulnerability.

Available Exploits

No exploits available for this CVE.

Related News

No news articles found for this CVE.

Affected Products

References

EU Vulnerability Database

Monitored by ENISA for EU cybersecurity

EU Coordination

Not EU Coordinated

Exploitation Status

No Known Exploitation

ENISA Analysis

Malicious code in bioql (PyPI)

Affected Products (ENISA)

vyperlang
vyper

ENISA Scoring

CVSS Score (3.1)

3.7
/10
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS Score

0.070
probability

Data provided by ENISA EU Vulnerability Database. Last updated: October 3, 2025

GitHub Security Advisories

Community-driven vulnerability intelligence from GitHub

✓ GitHub Reviewed MODERATE

Vyper: reversed order of side effects for some operations

GHSA-g2xh-c426-v8mf

Advisory Details

### Impact 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` For example: ```Vyper f:uint256 @internal def side_effect() -> uint256: self.f = 12 return 1 @external def foo() -> uint256: return unsafe_add(self.f,self.side_effect()) # returns 13 instead of 1 ``` ```Vyper a:DynArray[uint256, 12] @external def bar() -> bool: self.a = [1,2,3] return len(self.a) == self.a.pop() # return false instead of true ``` ### Patches not yet patched, will address in a future release. tracking in https://github.com/vyperlang/vyper/issues/3604. ### Workarounds When using expressions from the list above, 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. ### References _Are there any links users can visit to find out more?_

Affected Packages

PyPI vyper
ECOSYSTEM: ≥0 ≤0.4.2

CVSS Scoring

CVSS Score

5.0

CVSS Vector

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

Advisory provided by GitHub Security Advisory Database. Published: September 4, 2023, Modified: June 18, 2025

References

Published: 2023-09-04T17:39:12.822Z
Last Modified: 2024-11-19T16:46:23.708Z
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