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TI-2021-22763 Aliases CVE-2021-48020

Memory corruption in Vyper internal calls within arrays

Priority LOW 36CWE-787Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
—
Confidentiality · integrity · availability
None · High · Low
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

Vyper from 0.1.0b4 before 0.3.0 contains a memory corruption flaw (CWE-787) caused by an incorrect stack tip pointer when internal function calls appear inside arrays. Contracts that place internal calls in nested array elements, external call arguments, struct literals, or raw_log topics can have their memory corrupted, which makes the contract behave incorrectly. A remote attacker needs no privileges and no user interaction to trigger the flaw.

Written with Claude Haiku 5.5 from the sources below · 2026-11-03

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00284 21st percentileScored 2026-11-07
Fix Fixed vyper (vyperlang): 0.3.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
vyperlangvyper0.1.0b4 to before 0.3.00.3.0Patch availableCNA
  • vyper Vendorvyperlang Affected 0.1.0b4 to before 0.3.0 Fixed in 0.3.0 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:vyperlang:vyper:*:*:*:*:*:*:*:*——vyperlang
  • cpe:2.3:a:vyperlang:vyper:*:*:*:*:*:*:*:* Versions — — ·vyperlang

Remediation

Upgrade Vyper to version 0.3.0 or later.

Written with Claude Haiku 5.5 from the sources below · 2026-11-03

  • Fix · CNA vyper (vyperlang) Fixed in 0.3.0

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    vyperlang vyper 0.3.0

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2020-20047 Memory corruption in Vyper via nested internal function callsPriority LOW 36
    Show all 2 records →

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-21 Threatist record created from CVE-2021-48020
  2. 2026-10-22 Priority changed: MEDIUM → LOW
  3. 2026-10-28 CISA SSVC decision points changed
  4. 2026-11-03 Affected versions changed · Red Hat
  5. 2026-11-03 CVSS score added · Red Hat

References

Advisory 1

  • TI-2024-16182 Vyper bounds check on built-in `slice()` function can be overflowed CVSS 3.1CRITICAL 9.8
  • TI-2024-14992 concat built-in can corrupt memory in vyper CVSS 3.1CRITICAL 9.8
  • TI-2024-16184 Vyper array negative index vulnerability CVSS 3.1CRITICAL 9.8
  • TI-2022-08657 Integer bounds error in Vyper CVSS 3.1CRITICAL 9.8
  • TI-2022-11796 Multiple evaluation of contract address in call in vyper CVSS 3.1HIGH 8.2
  • TI-2026-78730 Optimizer miscompilation of msg.value | K in Vyper ternary branches CVSS 4.0HIGH 8.2
See all 52 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences