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TI-2021-22762 Aliases CVE-2021-48019

Incorrect RETURNDATASIZE in Vyper create_forwarder_to proxies

Priority LOW 28CWE-805Published · Updated

Key facts

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

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

Summary

Vyper before 0.2.9 deploys forwarder proxies through the built-in create_forwarder_to function, and these proxies report a fixed 4096-byte RETURNDATASIZE instead of the actual return data size. Calls through these proxies can yield corrupted data when a function returns more than 4096 bytes without return data sanitation, and they fail strict return-size checks such as SafeERC20.safeTransfer. The flaw is CWE-805, and an unauthenticated remote attacker can trigger it with low complexity, causing integrity and availability impact.

Written with Claude Haiku 5.5 from the sources below · 2026-11-02

Description from the CNA

Vyper before 0.2.9 deploys forwarder proxies through the built-in create_forwarder_to function that report a fixed 4096-byte RETURNDATASIZE rather than the actual return data size. Calls through these proxies can yield corrupted data when a function returns more than 4096 bytes without return data sanitation, and fail strict return-size checks such as SafeERC20.safeTransfer.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00248 16th percentileScored 2026-11-07
Fix Fixed vyper (vyperlang): 0.2.9

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
vyperlangvyperbefore 0.2.90.2.9Patch availableCNA
  • vyper Vendorvyperlang Affected before 0.2.9 Fixed in 0.2.9 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 0.2.9 or later, which fixes the flaw. The sources list no fixed version for Vyper proxies beyond this release.

Written with Claude Haiku 5.5 from the sources below · 2026-11-02

  • Fix · CNA vyper (vyperlang) Fixed in 0.2.9

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-2021-48019
  2. 2026-10-22 Priority changed: MEDIUM → LOW
  3. 2026-10-27 CISA SSVC decision points changed
  4. 2026-11-02 Affected versions changed · Red Hat
  5. 2026-11-02 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