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Medium

vyper performs double eval of raw_args in create_from_blueprint

  • Disclosed: 25.04.2024
  • Updated: 11.10.2026 12:20

Summary

Using the create_from_blueprint builtin can result in a double eval vulnerability when raw_args=True and the args argument has side-effects.

A contract search was performed and no vulnerable contracts were found in production. In particular, the raw_args variant of create_from_blueprint was not found to be used in production.

Details

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: https://github.com/vyperlang/vyper/blob/cedf7087e68e67c7bfbd47ae95dcb16b81ad2e02/vyper/builtins/functions.py#L1847

As such, it can be evaluated multiple times (instead of retrieving the value from the stack).

PoC

The vulnerability is demonstrated in the following boa test:

vyper
src1 = """
c: uint256
"""
deployer = """
created_address: public(address)
deployed: public(uint256)

@external
def get() -> Bytes[32]:
    self.deployed += 1
    return b''

@external
def create_(target: address):
    self.created_address = create_from_blueprint(target, raw_call(self, method_id("get()"), max_outsize=32), raw_args=True, code_offset=3)
"""

Factory = b.loads_partial(src1)
c = Factory.deploy_as_blueprint()

c2 = b.loads(deployer, b'')
c2.create_(c)
c2.deployed()

The output of c2.deployed() is 2 although create_ was called only once and the value was initialized to 0.

Patches

Patched in https://github.com/vyperlang/vyper/pull/3976.

Impact

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.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Python (PyPI) vyper < 0.4.0 0.4.0

References

CVSS score 5.3/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness (CWE)
CWE-95
Platform
Python (PyPI)
Package
vyper
Disclosed
25.04.2024
Updated
11.10.2026 12:20

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2024-208 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-3whq-64q2-qfj6 - CC BY 4.0

Vulnerability history: vyper

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (47) in the archive
Total entries
47
First → latest
03.2020 10.2026
Without a fix
5
Exploited in attacks
0

Severity breakdown

  • Critical 3
  • High 14
  • Medium 20
  • Low 10

Disclosures per year

Severity:
  1. vyper performs double eval of raw_args in create_from_blueprint this entry
    Medium · 5.3 CVE-2024-32647 < 0.4.0 0.4.0
  2. Vyper negative array index bounds checks
    Critical · 9.8 CVE-2024-24563 < 0.4.0 0.4.0
  3. Vyper's bounds check on built-in `slice()` function can be overflowed
    Critical · 9.8 CVE-2024-24561 < 0.4.0 0.4.0
  4. concat built-in can corrupt memory in vyper
    High · 7.3 CVE-2024-22419 >= 0.3.0, < 0.4.0 0.4.0
  5. incorrect storage layout for contracts containing large arrays
    High · 7.5 CVE-2023-46247 < 0.3.8 0.3.8
  6. Vyper vulnerable to memory corruption in certain builtins utilizing `msize`
    High · 8.1 CVE-2023-42443 >= 0.3.4, < 0.3.10 0.3.10
  7. Vyper has incorrectly allocated named re-entrancy locks
    Critical · 8.7 CVE-2023-39363 >= 0.2.15, < 0.3.1 0.3.1
  8. Vyper vulnerable to incorrect ordering of arguments for kwargs passed to internal calls
    High · 7.5 CVE-2023-32059 < 0.3.8 0.3.8
  9. Vyper vulnerable to integer overflow in loop
    High · 7.5 CVE-2023-32058 < 0.3.8 0.3.8
  10. Vyper vulnerable to OOB DynArray access when array is on both LHS and RHS of an assignment
    High · 7.5 CVE-2023-31146 < 0.3.8 0.3.8
  11. vyper vulnerable to storage allocator overflow
    High · 7.5 CVE-2023-30837 < 0.3.8 0.3.8
  12. Incorrect success value returned in vyper
    High · 7.5 CVE-2023-30629 >= 0.3.1, < 0.3.8 0.3.8
  13. Multiple evaluation of contract address in call in vyper
    High · 7.5 CVE-2022-29255 < 0.3.4 0.3.4
  14. Vyper is a pythonic Smart Contract Language for the ethereum virtual machine. In affected versions, the return of `<iface>.returns_int128()` is not validated to fall within the bounds of `int128`. Thi
    High · 8.8 CVE-2022-24845 < 0.3.2 0.3.2
  15. Buffer Overflow in vyper
    High · 7.1 CVE-2022-24788 < 0.3.2 0.3.2
  16. Incorrect Comparison in Vyper
    High · 7.5 CVE-2022-24787 < 0.3.2 0.3.2
  17. Memory corruption when returning a literal struct with a private call inside of it
    High · 7.5 CVE-2021-41121 < 0.3.0 0.3.0
  18. Storage corruption due to variables overwritten by re-entrancy locks
    High ghsa-7f92-rr6w-cq64 >= 0.2.13, < 0.2.15 0.2.15

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