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Back to active CVEs
High · CVSS 8.3CVE-2021-48020

Vyper before 0.3.0 Memory Corruption via Internal Function Calls in ArraysCVE-2021-48020

Answer in brief

CVE-2021-48020 records a High severity (CVSS 8.3) vulnerability in Vyper before 0.3.0 Memory Corruption via Internal Function Calls in Arrays. The current sources do not mark it as known exploited. The current feed maps vyperlang/vyper (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

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

Published Oct 21, 2026Updated Oct 21, 2026Source checked Oct 21, 2026First seen by HOL Oct 21, 2026Material review Oct 21, 2026
Upstream Advisory

Key facts

Risk
High · CVSS 8.3
Exploitation
Not marked as known exploited
Affected software
1 mapped package or product
Fix availability
Available

Why this deserves its current priority

CVSS is 8.3. 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 vyperlang/vyper (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
vyperlang/vypergeneric>=0.1.0b4 <0.3.00.3.0

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for vyperlang/vyper.
  2. 2Review the reported fix. Update vyperlang/vyper to 0.3.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Oct 21, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Oct 21, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Oct 21, 2026

Sources and claim methodology

  • GitHub security advisorygithub.com
  • Source referencevulncheck.com
Upstream source description

Vyper from 0.1.0b4 before 0.3.0 contains a memory corruption vulnerability caused by an incorrect stack tip pointer when internal function calls are performed inside arrays. Contracts placing internal calls in nested array elements, external call arguments, struct literals, or raw_log topics can have memory corrupted, producing incorrect contract behavior.

Quoted source text, attributed separately from HOL analysis.

Related CVEs

  • Vyper through 0.5.0b1 Literal Value Substitution via Multi-byte CharactersSame vyperlang/vyper package
  • Vyper 0.3.8 through 0.5.0b1 Memory Misread via Ternary Nested Array SelectionSame vyperlang/vyper package
  • Vyper through 0.5.0b1 Literal Value Manipulation via Line SeparatorsSame vyperlang/vyper package
  • Vyper 0.3.8 through 0.5.0b1 Optimizer Miscompilation of msg.value | K in Ternary BranchesSame vyperlang/vyper package
  • Vyper 0.3.4 through 0.5.0b1 create_from_blueprint Offset Validation Bypass via Unsigned WraparoundSame vyperlang/vyper package

Record context

Vulnerability class
Memory Corruption
EPSS
Not reported
CWE IDs
CWE-787
Source
CVE List V5
Source checked
Oct 21, 2026
References
2 linked sources
Open source record