What’s Vulnerable › Vulnerabilities

CVE-2018-18920

• Severity: high (CVSS 8.8 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2018-11-12 · updated 2026-06-17
• Weakness: CWE-119

Description

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."

Affected products

• ethereum Py-Evm: 0.2.0-alpha.33

References

• https://github.com/ethereum/py-evm/issues/1448
• https://twitter.com/AlexanderFisher/status/1060923428641878019
• https://twitter.com/NettaLab/status/1060889400102383617
• https://www.reddit.com/r/ethereum/comments/9vkk2g/netta_labs_claim_to_have_found_a_vulnerability_in/e9d3wyx/
• https://github.com/ethereum/py-evm/issues/1448
• https://twitter.com/AlexanderFisher/status/1060923428641878019
• https://twitter.com/NettaLab/status/1060889400102383617
• https://www.reddit.com/r/ethereum/comments/9vkk2g/netta_labs_claim_to_have_found_a_vulnerability_in/e9d3wyx/

Get alerted when CVE-2018-18920 or the next vulnerability affects your stack