github_osv/GHSA-4w26-8p97-f4jp
AugAssign evaluation order causing OOB write within the object in Vyper
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. In other words, the following code
```vyper
def poc():
a: DynArray[uint256, 2] = [1, 2]
a[1] += a.pop()
```
is equivalent to:
```vyper
def poc():
a: DynArray[uint256, 2] = [1, 2]
a[1] += a[len(a) - 1]
a.pop()
```
rather than:
```vyper
def poc():
a: DynArray[uint256, 2] = [1, 2]
s: uint256 = a[1]
t: uint256 = a.pop()
a[1] = s + t # reverts due to oob access
```
gitlab/pypi/vyper/CVE-2025-27105
AugAssign evaluation order causing OOB write within the object in Vyper
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. In other words, the following code
```vyper
def poc():
a: DynArray[uint256, 2] = [1, 2]
a[1] += a.pop()
```
is equivalent to:
```vyper
def poc():
a: DynArray[uint256, 2] = [1, 2]
a[1] += a[len(a) - 1]
a.pop()
```
rather than:
```vyper
def poc():
a: DynArray[uint256, 2] = [1, 2]
s: uint256 = a[1]
t: uint256 = a.pop()
a[1] = s + t # reverts due to oob access
```
pypa/vyper/PYSEC-2025-31
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.
pysec/PYSEC-2025-31
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.