CVE-2018-18920

Name: CVE-2018-18920
Creator: NVD / NIST
Published: 2018-11-12T02:29:00.233+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 2.90%

Last modified Jun 17, 2026

CVE-2018-18920 is a vulnerability of currently unknown severity. 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.". EPSS estimates a 2.90% chance of exploitation in the next 30 days.

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."

Metrics

EPSS Probability

2.90%

85.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-119

Affected Software

Vendor	Product	Versions	Update
Ethereum	Py-Evm	0.2.0	Alpha.33

References

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

Timeline

Published: Nov 12, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-18920?

How severe is CVE-2018-18920?

Severity scoring for CVE-2018-18920 is pending analysis. The EPSS model estimates a 2.90% probability of exploitation in the next 30 days.

How do I fix CVE-2018-18920?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2018-18920?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST