Vyper has incorrect re-entrancy lock when key is empty string (CVE-2023-42441) | HOL Guard CVE

Medium · CVSS 5.3CVE-2023-42441GHSA-3HG2-R75X-G69M

Vyper has incorrect re-entrancy lock when key is empty string

Answer in brief

CVE-2023-42441 records a Medium severity (CVSS 5.3) vulnerability in Vyper has incorrect re-entrancy lock when key is empty string. The current sources do not mark it as known exploited. The current feed maps vyper (pypi). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 18, 2023Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Sep 10, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps vyper (pypi). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
vyperpypi	>=0.2.9 <0.3.10	0.3.10

Recommended response

Check inventory. Check lockfiles and deployed manifests for vyper.
Review the reported fix. Update vyper to 0.3.10 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 18, 2023
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

### Impact Locks of the type `@nonreentrant("")` or `@nonreentrant('')` do not produce reentrancy checks at runtime. ```Vyper @nonreentrant("") # unprotected @external def bar(): pass @nonreentrant("lock") # protected @external def foo(): pass ``` ### Patches Patched in #3605 ### Workarounds The lock name should be a non-empty string. ### References _Are there any links users can visit to find out more?_

Quoted source text, attributed separately from HOL analysis.