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Vulnerability · Published Apr 25, 2024 · Assigned by GitHub_M

CVE-2024-32481vyper's range(start, start + N) reverts for negative numbers

Medium 5.3

In plain English

A medium-severity security flaw in vyper from vyperlang. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 57% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.8%top 43.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

Vyper is a pythonic Smart Contract Language for the Ethereum virtual machine. Starting in version 0.3.8 and prior to version 0.4.0b1, when looping over a `range` of the form `range(start, start + N)`, if `start` is negative, the execution will always revert. This issue is caused by an incorrect assertion inserted by the code generation of the range `stmt.parse_For_range()`. The issue arises when `start` is signed, instead of using `sle`, `le` is used and `start` is interpreted as an unsigned integer for the comparison. If it is a negative number, its 255th bit is set to `1` and is hence interpreted as a very large unsigned integer making the assertion always fail. Any contract having a `range(start, start + N)` where `start` is a signed integer with the possibility for `start` to be negative is affected. If a call goes through the loop while supplying a negative `start` the execution will revert. Version 0.4.0b1 fixes the issue.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
PyPIvyper0.4.0GHSA-ppx5-q359-pvwj
PyPIvyper0.4.0b1PYSEC-2024-246

Affected products (as reported)

VendorProductVersions
vyperlang vyper >= 0.3.8, < 0.4.0b1

Weakness: CWE-681 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References