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CVE-2023-32059

Vyper vulnerable to incorrect ordering of arguments for kwargs passed to internal calls

7.5 HighFix available

Vyper is a Pythonic smart contract language for the Ethereum virtual machine. Prior to version 0.3.8, internal calls with default arguments are compiled incorrectly. Depending on the number of arguments provided in the call, the defaults are added not right-to-left, but left-to-right. If the types are incompatible, typechecking is bypassed. The ability to pass kwargs to internal functions is an undocumented feature that is not well known about. The issue is patched in version 0.3.8.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
High
Availability
None

Exploit likelihood

0.73%Up 0.7 points since May 12, 2023
90%50%10%1%

What each source reports

CVE List Score used 7.5

Vyper vulnerable to incorrect ordering of arguments for kwargs passed to internal calls

Vyper is a Pythonic smart contract language for the Ethereum virtual machine. Prior to version 0.3.8, internal calls with default arguments are compiled incorrectly. Depending on the number of arguments provided in the call, the defaults are added not right-to-left, but left-to-right. If the types are incompatible, typechecking is bypassed. The ability to pass kwargs to internal functions is an undocumented feature that is not well known about. The issue is patched in version 0.3.8.

Record
CVE-2023-32059
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-683
Updated
2026-11-02
EUVDEUVD-2023-0272 7.5

Vyper is a Pythonic smart contract language for the Ethereum virtual machine. Prior to version 0.3.8, internal calls with default arguments are compiled incorrectly. Depending on the number of arguments provided in the call, the defaults are added not right-to-left, but left-to-right. If the types are incompatible, typechecking is bypassed. The ability to pass kwargs to internal functions is an undocumented feature that is not well known about. The issue is patched in version 0.3.8.

Record
EUVD-2023-0272
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-ph9x-4vc9-m39g 8.7

Vyper vulnerable to incorrect ordering of arguments for kwargs passed to internal calls

Impact

Internal calls to internal functions with more than 1 default argument are compiled incorrectly. Depending on the number of arguments provided in the call, the defaults are added not right-to-left, but left-to-right. If the types are incompatible, typechecking is bypassed. In the bar() function in the following code, self.foo(13) is compiled to self.foo(13,12) instead of self.foo(13,1337).

@internal
def foo(a:uint256 = 12, b:uint256 = 1337):
    pass

@internal
def bar():
    self.foo(13)

note that at the time of publication, the ability to pass kwargs to internal functions is an undocumented feature that does not seem to be widely used.

Patches

patched in c3e68c302aa6e1429946473769dd1232145822ac

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?

Record
GHSA-ph9x-4vc9-m39g
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-683
Updated
2026-11-02
NVD 7.5

Vyper is a Pythonic smart contract language for the Ethereum virtual machine. Prior to version 0.3.8, internal calls with default arguments are compiled incorrectly. Depending on the number of arguments provided in the call, the defaults are added not right-to-left, but left-to-right. If the types are incompatible, typechecking is bypassed. The ability to pass kwargs to internal functions is an undocumented feature that is not well known about. The issue is patched in version 0.3.8.

Record
CVE-2023-32059
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-683
Updated
2026-11-02
OSV 7.5

Vyper vulnerable to incorrect ordering of arguments for kwargs passed to internal calls

Vyper is a Pythonic smart contract language for the Ethereum virtual machine. Prior to version 0.3.8, internal calls with default arguments are compiled incorrectly. Depending on the number of arguments provided in the call, the defaults are added not right-to-left, but left-to-right. If the types are incompatible, typechecking is bypassed. The ability to pass kwargs to internal functions is an undocumented feature that is not well known about. The issue is patched in version 0.3.8.

Record
CVE-2023-32059
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-683
Updated
2026-11-02
OSVGHSA-ph9x-4vc9-m39g 8.7

Vyper vulnerable to incorrect ordering of arguments for kwargs passed to internal calls

Impact

Internal calls to internal functions with more than 1 default argument are compiled incorrectly. Depending on the number of arguments provided in the call, the defaults are added not right-to-left, but left-to-right. If the types are incompatible, typechecking is bypassed. In the bar() function in the following code, self.foo(13) is compiled to self.foo(13,12) instead of self.foo(13,1337).

@internal
def foo(a:uint256 = 12, b:uint256 = 1337):
    pass

@internal
def bar():
    self.foo(13)

note that at the time of publication, the ability to pass kwargs to internal functions is an undocumented feature that does not seem to be widely used.

Patches

patched in c3e68c302aa6e1429946473769dd1232145822ac

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?

Record
GHSA-ph9x-4vc9-m39g
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness
CWE-683
Updated
2026-11-02
OSVPYSEC-2023-79 No score

Vyper is a Pythonic smart contract language for the Ethereum virtual machine. Prior to version 0.3.8, internal calls with default arguments are compiled incorrectly. Depending on the number of arguments provided in the call, the defaults are added not right-to-left, but left-to-right. If the types are incompatible, typechecking is bypassed. The ability to pass kwargs to internal functions is an undocumented feature that is not well known about. The issue is patched in version 0.3.8.

Record
PYSEC-2023-79
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
vyper
PyPI
 before 0.3.8
0.3.8
vyper
PyPI
 before 0.3.8, plus listed versions
0.1.0b10.1.0b100.1.0b110.1.0b120.1.0b13
Show 36 moreShow less
0.1.0b140.1.0b150.1.0b160.1.0b170.1.0b20.1.0b30.1.0b40.1.0b50.1.0b60.1.0b70.1.0b80.1.0b90.2.10.2.100.2.110.2.120.2.130.2.140.2.150.2.160.2.20.2.30.2.40.2.50.2.60.2.70.2.80.2.90.3.00.3.10.3.20.3.30.3.40.3.50.3.60.3.7
0.3.8

History

History
RecordedChangedSources
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2023-32059 is a high vulnerability (CVSS 7.5) in Vyperlang Vyper, published May 11, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.73%, the 54th percentile. Fixed in vyper 0.3.8.

References

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