Every CVE Search/ Get API key

CVE-2018-18920

Py-EVM is vulnerable to arbitrary bytecode injection

8.8 HighFix available

Py-EVM v0.2.0-alpha.33 allows attackers to make a vm.execute_bytecode call that triggers computation._stack.values with '"stack": [100, 100, 0]' where b'\x' was expected, resulting in an execution failure because of an invalid opcode. This is reportedly related to "smart contracts can be executed indefinitely without gas being paid."

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

2.93%Up 1.1 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 8.8

Py-EVM v0.2.0-alpha.33 allows attackers to make a vm.execute_bytecode call that triggers computation._stack.values with '"stack": [100, 100, 0]' where b'\x' was expected, resulting in an execution failure because of an invalid opcode. This is reportedly related to "smart contracts can be executed indefinitely without gas being paid."

Record
CVE-2018-18920
CVSS 3.0
8.8 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS 2.0
6.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:P
Weakness
CWE-119
Updated
2026-11-02
CVE List No score

Py-EVM v0.2.0-alpha.33 allows attackers to make a vm.execute_bytecode call that triggers computation._stack.values with '"stack": [100, 100, 0]' where b'\x' was expected, resulting in an execution failure because of an invalid opcode. This is reportedly related to "smart contracts can be executed indefinitely without gas being paid."

Record
CVE-2018-18920
Updated
2026-11-02
EUVDEUVD-2018-0118 No score

Py-EVM v0.2.0-alpha.33 allows attackers to make a vm.execute_bytecode call that triggers computation._stack.values with '"stack": [100, 100, 0]' where b'\x' was expected, resulting in an execution failure because of an invalid opcode. This is reportedly related to "smart contracts can be executed indefinitely without gas being paid."

Record
EUVD-2018-0118
Updated
2026-11-03
GitHub AdvisoriesGHSA-vqgp-4jgj-5j64 8.7

Py-EVM is vulnerable to arbitrary bytecode injection

Py-EVM v0.2.0-alpha.33 allows attackers to make a vm.execute_bytecode call that triggers computation._stack.values with '"stack": [100, 100, 0]' where b'\x' was expected, resulting in an execution failure because of an invalid opcode. This is reportedly related to "smart contracts can be executed indefinitely without gas being paid."

Record
GHSA-vqgp-4jgj-5j64
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.0
8.8 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-119
Updated
2026-11-02
OSV 8.8

Py-EVM v0.2.0-alpha.33 allows attackers to make a vm.execute_bytecode call that triggers computation._stack.values with '"stack": [100, 100, 0]' where b'\x' was expected, resulting in an execution failure because of an invalid opcode. This is reportedly related to "smart contracts can be executed indefinitely without gas being paid."

Record
CVE-2018-18920
CVSS 3.0
8.8 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVGHSA-vqgp-4jgj-5j64 8.7

Py-EVM is vulnerable to arbitrary bytecode injection

Py-EVM v0.2.0-alpha.33 allows attackers to make a vm.execute_bytecode call that triggers computation._stack.values with '"stack": [100, 100, 0]' where b'\x' was expected, resulting in an execution failure because of an invalid opcode. This is reportedly related to "smart contracts can be executed indefinitely without gas being paid."

Record
GHSA-vqgp-4jgj-5j64
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.0
8.8 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-119
Updated
2026-11-02
OSVPYSEC-2018-155 8.8

Py-EVM v0.2.0-alpha.33 allows attackers to make a vm.execute_bytecode call that triggers computation._stack.values with '"stack": [100, 100, 0]' where b'\x' was expected, resulting in an execution failure because of an invalid opcode. This is reportedly related to "smart contracts can be executed indefinitely without gas being paid."

Record
PYSEC-2018-155
CVSS 3.0
8.8 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVPYSEC-2018-96 No score

Py-EVM v0.2.0-alpha.33 allows attackers to make a vm.execute_bytecode call that triggers computation._stack.values with '"stack": [100, 100, 0]' where b'\x' was expected, resulting in an execution failure because of an invalid opcode. This is reportedly related to "smart contracts can be executed indefinitely without gas being paid."

Record
PYSEC-2018-96
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
py-evm
PyPI
 through 0.2.0a33 None known
py-evm
PyPI
 through 0.2.0a33, plus listed versions
0.2.0a10.2.0a100.2.0a110.2.0a120.2.0a13
Show 22 moreShow less
0.2.0a140.2.0a150.2.0a160.2.0a170.2.0a180.2.0a190.2.0a200.2.0a210.2.0a220.2.0a240.2.0a250.2.0a260.2.0a280.2.0a290.2.0a30.2.0a300.2.0a310.2.0a320.2.0a50.2.0a70.2.0a80.2.0a9
 None known
evm-py
PyPI
 through 0.2.0-alpha\.33 None known
py-evm
PyPI
 before 0.2.0a33, plus listed versions
0.2.0a10.2.0a100.2.0a110.2.0a120.2.0a13
Show 22 moreShow less
0.2.0a140.2.0a150.2.0a160.2.0a170.2.0a180.2.0a190.2.0a200.2.0a210.2.0a220.2.0a240.2.0a250.2.0a260.2.0a280.2.0a290.2.0a30.2.0a300.2.0a310.2.0a320.2.0a50.2.0a70.2.0a80.2.0a9
0.2.0a33

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

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

In short

CVE-2018-18920 is a high vulnerability (CVSS 8.8) in Ethereum Py-evm, published November 12, 2018. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.93%, the 87th percentile. Fixed in py-evm 0.2.0a33.

References

Pages All vulnerabilities Browse Docs Sources Guide Get API key
MoveEnter Open