title: Vyper's raw_call with outsize=0 and revert_on_failure=False returns incorrect success value
description: Vyper is a Pythonic Smart Contract Language for the ethereum virtual machine. In versions 0.3.1 through 0.3.7, the Vyper compiler generates the wrong bytecode. Any contract that uses the `raw_call` with `revert_on_failure=False` and `max_outsize=0` receives the wrong response from `raw_call`. Depending on the memory garbage, the result can be either `True` or `False`. A patch is available and, as of time of publication, anticipated to be part of Vyper 0.3.8. As a workaround, one may always put  `max_outsize>0`.
problem types: CWE-670: Always-Incorrect Control Flow Implementation
affected:
{
vendor: vyperlang
product: vyper
versions:
version: >= 0.3.1, <= 0.3.7, status: affected
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 7.5
baseSeverity: HIGH
confidentialityImpact: NONE
integrityImpact: HIGH
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
version: 3.1
]