CVE-2022-29255

Multiple evaluation of contract address in call in vyper

Workarounds

assign contract addresses to variables. the above example would change to

@external
def do_stuff():
    t: Foo = Foo(msg.sender).bar()
    t.foo()

References

For more information

when a calling an external contract with no return value, the contract address could be evaluated twice. this is usually only an efficiency problem, but if evaluation of the contract address has side effects, it could result in double evaluation of the side effects.

in the following example, Foo(msg.sender).bar() is the contract address for the following call (to .foo()), and could get evaluated twice

interface Foo:
    def foo(): nonpayable
    def bar() -> address: nonpayable

@external
def do_stuff():
    Foo(Foo(msg.sender).bar()).foo()

CVE-2022-29255 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 (0.3.4); upgrading removes the vulnerable code path.

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1. What is CVE-2022-29255? CVE-2022-29255 is a high-severity security vulnerability in vyper (pip), affecting versions < 0.3.4. It is fixed in 0.3.4.
2. How severe is CVE-2022-29255? CVE-2022-29255 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-2022-29255? vyper (pip) versions < 0.3.4 is affected.
4. Is there a fix for CVE-2022-29255? Yes. CVE-2022-29255 is fixed in 0.3.4. Upgrade to this version or later.
5. Is CVE-2022-29255 exploitable, and should I be worried? Whether CVE-2022-29255 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-2022-29255 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-2022-29255? Upgrade vyper to 0.3.4 or later.

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