Vyper vulnerable to memory corruption in certain builtins utilizing msize

Exploitation

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

CVSS

8.1 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2023-42443: 0.83% estimated exploitation activity in the next 30 days; percentile 57.66 (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 In certain conditions, the memory used by the builtins rawcall, createfromblueprint and createcopyof can be corrupted. - For rawcall, the argument buffer of the call can be corrupted, leading to incorrect calldata in the sub-context. - For createfromblueprint and createcopyof, the buffer for the to-be-deployed bytecode can be corrupted, leading to deploying incorrect bytecode. Below are the conditions that must be fulfilled for the corruption to happen for each builtin: rawcall - memory is not fully initialized, ex. all parameters to an external function live in calldata and - The data argument of the builtin is msg.data. and - The to, value or gas passed to the builtin is some complex expression that results in writing to uninitialized memory (e.g. calling an internal function) createcopyof - memory is not fully initialized, ex. all parameters to an external function live in calldata and - The value or salt passed to the builtin is some complex expression that results in…

Published by the source

20 Sep 2023, 23:05 UTC

Last modified by the source

22 Nov 2024, 20:45 UTC

Source last checked

26 Oct 2026, 13:27 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-c647-pxm2-c52w

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-c647-pxm2-c52w

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# Patch Next advisory brief: CVE-2023-42443

Advisory: Vyper vulnerable to memory corruption in certain builtins utilizing `msize`
IDs: CVE-2023-42443, GHSA-c647-pxm2-c52w
Record: https://patchnext.com/advisories/cve-2023-42443 (revision 2, source checked 26 Oct 2026, 13:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: vyper 0.3.10. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI vyper: affected >= 0.3.4, <= 0.3.9; fixed in 0.3.10

## 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://osv.dev/vulnerability/GHSA-c647-pxm2-c52w (OSV record GHSA-c647-pxm2-c52w lists affected ranges: PyPI vyper >=0.3.4 <0.3.10 (fixed))
- Verified: https://github.com/advisories/GHSA-c647-pxm2-c52w (GitHub-reviewed advisory GHSA-c647-pxm2-c52w lists affected ranges: PyPI vyper >=0.3.4 <=0.3.9)

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