Vyper: Call stack corruption when passing complex type containing non-base type members as argument

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2020-37287: 0.25% estimated exploitation activity in the next 30 days; percentile 16.68 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact When we pass a multi-dimensional array (like [[1, 2], [3, 4]]) as an argument to internal/external functions we get incorrect output. This is due to a stack management issue, because it was assumed that the size of each subtype of an array/struct is 32, which is not always correct. Example code: Please see #2183 for further information Patches This problem was fixed in #2184, and released as a part of v0.2.6.

Published by the source

6 Oct 2026, 15:22 UTC

Last modified by the source

24 Oct 2026, 02:56 UTC

Source last checked

26 Oct 2026, 13:55 UTC

1. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4v7v-gqf9-ww2g

2. Revision 3 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-4v7v-gqf9-ww2g

4. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-4v7v-gqf9-ww2g

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# Patch Next advisory brief: CVE-2020-37287

Advisory: Vyper: Call stack corruption when passing complex type containing non-base type members as argument
IDs: CVE-2020-37287, GHSA-4v7v-gqf9-ww2g
Record: https://patchnext.com/advisories/ghsa-4v7v-gqf9-ww2g (revision 4, source checked 26 Oct 2026, 13:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: vyper 0.2.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI vyper: affected < 0.2.6; fixed in 0.2.6

## Suggested inspection (read-only)
- `python -m pip show vyper`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on vyper.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4v7v-gqf9-ww2g (GitHub-reviewed advisory GHSA-4v7v-gqf9-ww2g lists affected ranges: PyPI vyper >=0 <0.2.6)
- Verified: https://osv.dev/vulnerability/GHSA-4v7v-gqf9-ww2g (OSV record GHSA-4v7v-gqf9-ww2g lists affected ranges: PyPI vyper >=0 <0.2.6 (fixed))

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