First published: Thu May 11 2023(Updated: )
### Impact during codegen, the length word of a dynarray is written before the data, which can result in OOB array access in the case where the dynarray is on both the lhs and rhs of an assignment. here is a minimal example producing the issue: ```vyper a:DynArray[uint256,3] @external def test() -> DynArray[uint256,3]: self.a = [1,2,3] self.a = empty(DynArray[uint256,3]) self.a = [self.a[0],self.a[1],self.a[2]] return self.a # return [1,2,3] ``` and here is an example demonstrating the issue can cause data corruption across call frames: ```vyper @external def test() -> DynArray[uint256,3]: self.a() return self.b() # return [1,2,3] @internal def a(): a: uint256 = 0 b: uint256 = 1 c: uint256 = 2 d: uint256 = 3 @internal def b() -> DynArray[uint256,3]: a: DynArray[uint256,3] = empty(DynArray[uint256,3]) a = [a[0],a[1],a[2]] return a ``` examples involving append and pop: ```vyper @internal def foo(): c: DynArray[uint256, 1] = [] c.append(c[0]) ``` ```vyper @internal def foo(): c: DynArray[uint256, 1] = [1] c[0] = c.pop() ``` the expected behavior in all of the above cases is to revert due to oob array access. ### Patches patched in 4f8289a81206f767df1900ac48f485d90fc87edb ### Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_ ### References _Are there any links users can visit to find out more?_
Credit: security-advisories@github.com security-advisories@github.com security-advisories@github.com
Affected Software | Affected Version | How to fix |
---|---|---|
pip/vyper | <0.3.8 | 0.3.8 |
Vyperlang Vyper | <0.3.8 |
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CVE-2023-31146 is a vulnerability in the Vyper smart contract language for the Ethereum virtual machine.
CVE-2023-31146 has a severity rating of critical (9.1).
The affected software for CVE-2023-31146 is Vyper version up to exclusive 0.3.8.
This vulnerability can be exploited by performing out-of-bounds array access in the case where a dynarray is on both the lhs and rhs of an assignment.
To fix CVE-2023-31146, upgrade to Vyper version 0.3.8 or later.