Vyperlang: >> Vyper >> 0.3.0 Security Vulnerabilities
vyper is a Pythonic Smart Contract Language for the EVM. Vyper `sqrt()` builtin uses the babylonian method to calculate square roots of decimals. Unfortunately, improper handling of the oscillating final states may lead to sqrt incorrectly returning rounded up results. This issue is being addressed and a fix is expected in version 0.4.1. Users are advised to upgrade as soon as the patched release is available. There are no known workarounds for this vulnerability.
CVSS Score
7.5
EPSS Score
0.0
Published
2025-02-21
vyper is a Pythonic Smart Contract Language for the EVM. Multiple evaluation of a single expression is possible in the iterator target of a for loop. While the iterator expression cannot produce multiple writes, it can consume side effects produced in the loop body (e.g. read a storage variable updated in the loop body) and thus lead to unexpected program behavior. Specifically, reads in iterators which contain an ifexp (e.g. `for s: uint256 in ([read(), read()] if True else [])`) may interleave reads with writes in the loop body. Vyper for loops allow two kinds of iterator targets, namely the `range()` builtin and an iterable type, like SArray and DArray. During codegen, iterable lists are required to not produce any side-effects (in the following code, `range_scope` forces `iter_list` to be parsed in a constant context, which is checked against `is_constant`). However, this does not prevent the iterator from consuming side effects provided by the body of the loop. For SArrays on the other hand, `iter_list` is instantiated in the body of a `repeat` ir, so it can be evaluated several times. This issue is being addressed and is expected to be available in version 0.4.1. Users are advised to upgrade as soon as the patched release is available. There are no known workarounds for this vulnerability.
CVSS Score
7.5
EPSS Score
0.001
Published
2025-02-21
vyper is a Pythonic Smart Contract Language for the EVM. Vyper handles AugAssign statements by first caching the target location to avoid double evaluation. However, in the case when target is an access to a DynArray and the rhs modifies the array, the cached target will evaluate first, and the bounds check will not be re-evaluated during the write portion of the statement. This issue has been addressed in version 0.4.1 and all users are advised to upgrade. There are no known workarounds for this vulnerability.
CVSS Score
9.1
EPSS Score
0.001
Published
2025-02-21
Vyper is a pythonic Smart Contract Language for the Ethereum virtual machine. In versions 0.3.10 and prior, using the `sqrt` builtin can result in double eval vulnerability when the argument has side-effects. It can be seen that the `build_IR` function of the `sqrt` builtin doesn't cache the argument to the stack. As such, it can be evaluated multiple times (instead of retrieving the value from the stack). No vulnerable production contracts were found. Additionally, double evaluation of side-effects should be easily discoverable in client tests. As such, the impact is low. As of time of publication, no fixed versions are available.
CVSS Score
5.3
EPSS Score
0.009
Published
2024-04-25
Vyper is a pythonic Smart Contract Language for the Ethereum virtual machine. In versions 0.3.10 and prior, incorrect values can be logged when `raw_log` builtin is called with memory or storage arguments to be used as topics. A contract search was performed and no vulnerable contracts were found in production. The `build_IR` function of the `RawLog` class fails to properly unwrap the variables provided as topics. Consequently, incorrect values are logged as topics. As of time of publication, no fixed version is available.
CVSS Score
5.3
EPSS Score
0.008
Published
2024-04-25
Vyper is a pythonic Smart Contract Language for the Ethereum virtual machine. In versions 0.3.10 and prior, using the `slice` builtin can result in a double eval vulnerability when the buffer argument is either `msg.data`, `self.code` or `<address>.code` and either the `start` or `length` arguments have side-effects. It can be easily triggered only with the versions `<0.3.4` as `0.3.4` introduced the unique symbol fence. No vulnerable production contracts were found. Additionally, double evaluation of side-effects should be easily discoverable in client tests. As such, the impact is low. As of time of publication, no fixed versions are available.
CVSS Score
5.3
EPSS Score
0.008
Published
2024-04-25
Vyper is a pythonic Smart Contract Language for the Ethereum virtual machine. In versions 0.3.10 and prior, using the `create_from_blueprint` builtin can result in a double eval vulnerability when `raw_args=True` and the `args` argument has side-effects. It can be seen that the `_build_create_IR` function of the `create_from_blueprint` builtin doesn't cache the mentioned `args` argument to the stack. As such, it can be evaluated multiple times (instead of retrieving the value from the stack). No vulnerable production contracts were found. Additionally, double evaluation of side-effects should be easily discoverable in client tests. As such, the impact is low. As of time of publication, no fixed versions exist.
CVSS Score
5.3
EPSS Score
0.007
Published
2024-04-25
Vyper is a pythonic Smart Contract Language for the ethereum virtual machine. When using the built-in `extract32(b, start)`, if the `start` index provided has for side effect to update `b`, the byte array to extract `32` bytes from, it could be that some dirty memory is read and returned by `extract32`. This vulnerability is fixed in 0.4.0.
CVSS Score
3.7
EPSS Score
0.005
Published
2024-02-26
Vyper is a pythonic Smart Contract Language for the ethereum virtual machine. If an excessively large value is specified as the starting index for an array in `_abi_decode`, it can cause the read position to overflow. This results in the decoding of values outside the intended array bounds, potentially leading to exploitations in contracts that use arrays within `_abi_decode`. This vulnerability affects 0.3.10 and earlier versions.
CVSS Score
3.7
EPSS Score
0.004
Published
2024-02-26
Vyper is a Pythonic Smart Contract Language for the Ethereum Virtual Machine. Arrays can be keyed by a signed integer, while they are defined for unsigned integers only. The typechecker doesn't throw when spotting the usage of an `int` as an index for an array. The typechecker allows the usage of signed integers to be used as indexes to arrays. The vulnerability is present in different forms in all versions, including `0.3.10`. For ints, the 2's complement representation is used. Because the array was declared very large, the bounds checking will pass Negative values will simply be represented as very large numbers. As of time of publication, a fixed version does not exist.
There are three potential vulnerability classes: unpredictable behavior, accessing inaccessible elements and denial of service. Class 1: If it is possible to index an array with a negative integer without reverting, this is most likely not anticipated by the developer and such accesses can cause unpredictable behavior for the contract. Class 2: If a contract has an invariant in the form `assert index < x`, the developer will suppose that no elements on indexes `y | y >= x` are accessible. However, by using negative indexes, this can be bypassed. Class 3: If the index is dependent on the state of the contract, this poses a risk of denial of service. If the state of the contract can be manipulated in such way that the index will be forced to be negative, the array access can always revert (because most likely the array won't be declared extremely large). However, all these the scenarios are highly unlikely. Most likely behavior is a revert on the bounds check.
CVSS Score
9.8
EPSS Score
0.002
Published
2024-02-07
Page 1