What’s Vulnerable › Vulnerabilities

CVE-2023-30629: Vyper's raw_call with outsize=0 and revert_on_failure=False returns incorrect success value

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2023-04-24 · updated 2026-06-17
• Weakness: CWE-670

Description

Vyper is a Pythonic Smart Contract Language for the ethereum virtual machine. In versions 0.3.1 through 0.3.7, the Vyper compiler generates the wrong bytecode. Any contract that uses the `raw_call` with `revert_on_failure=False` and `max_outsize=0` receives the wrong response from `raw_call`. Depending on the memory garbage, the result can be either `True` or `False`. A patch is available and, as of time of publication, anticipated to be part of Vyper 0.3.8. As a workaround, one may always put `max_outsize>0`.

Affected products

• vyperlang vyper: from 0.3.1 before 0.3.8 — fixed in 0.3.8

How to fix

Upgrade to a fixed version: vyperlang vyper 0.3.8. Check the vendor advisory for mitigations.

References

• https://docs.vyperlang.org/en/v0.3.7/built-in-functions.html#raw_call
• https://github.com/lidofinance/gate-seals/blob/051593e74df01a4131c485b4fda52e691cd4b7d8/contracts/GateSeal.vy#L164
• https://github.com/lidofinance/gate-seals/pull/5/files
• https://github.com/vyperlang/vyper/commit/851f7a1b3aa2a36fd041e3d0ed38f9355a58c8ae
• https://github.com/vyperlang/vyper/security/advisories/GHSA-w9g2-3w7p-72g9
• https://docs.vyperlang.org/en/v0.3.7/built-in-functions.html#raw_call
• https://github.com/lidofinance/gate-seals/blob/051593e74df01a4131c485b4fda52e691cd4b7d8/contracts/GateSeal.vy#L164
• https://github.com/lidofinance/gate-seals/pull/5/files
• https://github.com/vyperlang/vyper/commit/851f7a1b3aa2a36fd041e3d0ed38f9355a58c8ae
• https://github.com/vyperlang/vyper/security/advisories/GHSA-w9g2-3w7p-72g9

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