CVE-2023-30837

vyper vulnerable to storage allocator overflow

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?

The storage allocator does not guard against allocation overflows. This can result in vulnerabilities like the following:

owner: public(address)
take_up_some_space: public(uint256[10])
buffer: public(uint256[max_value(uint256)])

@external
def initialize():
    self.owner = msg.sender

@external
def foo(idx: uint256, data: uint256):
    self.buffer[idx] = data

Per @toonvanhove, "An attacker can overwrite the owner variable by calling this contract with calldata: 0x04bc52f8 fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff5 ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff (spaces inserted for readability)
0x04bc52f8 is the selector for foo(uint256, uint256), and the last argument fff...fff is the new value for the owner variable."

CVE-2023-30837 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.3.8); upgrading removes the vulnerable code path.

Kodem intelligence

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patched in 0bb7203b584e771b23536ba065a6efda457161bb

1. What is CVE-2023-30837? CVE-2023-30837 is a high-severity security vulnerability in vyper (pip), affecting versions < 0.3.8. It is fixed in 0.3.8.
2. How severe is CVE-2023-30837? CVE-2023-30837 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of vyper are affected by CVE-2023-30837? vyper (pip) versions < 0.3.8 is affected.
4. Is there a fix for CVE-2023-30837? Yes. CVE-2023-30837 is fixed in 0.3.8. Upgrade to this version or later.
5. Is CVE-2023-30837 exploitable, and should I be worried? Whether CVE-2023-30837 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-30837 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-30837? Upgrade vyper to 0.3.8 or later.

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