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CVE-2021-48019

Vyper before 0.2.9 Incorrect RETURNDATASIZE in create_forwarder_to Proxies

CVSS score

6.3

EPSS probability

—

Risk score

0.6

Published

5 h ago

Patch status has not yet been verified

Resmî kaynaklarda yeterli kanıt bulunamadı. Bu sonuç “yama yok” anlamına gelmez.

Impact on My Inventory

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Vulnerability description

DayBreach AI Explanation

Verified against sources

Vyper pre‑0.2.9 RETURNDATASIZE bug

Sources read

2

Source agreement

0/2

Evidence confidence

%44

Short explanation

Vyper versions prior to 0.2.9 use create_forwarder_to proxies that always report a 4096‑byte RETURNDATASIZE, regardless of actual return size. Calls through such proxies can return corrupted data when the underlying function returns more than 4096 bytes, breaking strict size checks like SafeERC20.safeTransfer.

Why does it matter?

Corrupted return data can cause token transfer failures and undermine contract logic that relies on exact return sizes.

What should be done?

  • Upgrade Vyper to version 0.2.9 or later
  • Follow the vendor security advisory
  • Test functions that return large data
  • Consider alternative proxy implementations
  • Update contract code where needed
Note on uncertainty

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Chain of evidence and sources3 verified claims

Vyper 0.2.9 öncesi sürümler, create_forwarder_to proxy’lerinde sabit 4096 bayt RETURNDATASIZE bildirir (S0, S1).

Bu durum, 4096 bayttan fazla veri döndüren fonksiyonlarda bozuk veri ve SafeERC20.safeTransfer gibi sıkı kontrollerin başarısız olmasına yol açabilir (S0).

Yama durumu resmi kaynaklarda doğrulanamadı; durum UNKNOWN olarak rapor edilmiştir (S0).

Show the technical text from the sources

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.

CVSS vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

CWE: CWE-805

This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2021-48019 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1vyperlangvyper View
Total affected vendors: 1|Products: 1

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
6.3CVSS V4_0MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:NCVE CNA
6.3CVSS V40MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XNVD
4.8CVSS V3_1MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:LCVE CNA
4.8CVSS V31MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:LNVD

Patch and Remediation Guide

Solution & Remediation Advisory

Patch status unknown

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Until a patch is confirmed, follow the vendor advisory; do not read an unknown status as “no patch”.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-48019 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-48019 weaknesses.

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsGerekmiyor
UserGerekmiyor

Official Sources and Advisories

CVSS Vector Radar Chart

6.3 / 10
Attack VectorNetworkComplexityLowPrivilegesNoneUser Interact.NoneConfidentialityLowIntegrityNoneAvailabilityLow

Vulnerability Scoring Details

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone required
User InteractionNone required
Confidentiality (Gizlilik)Low
Integrity (Bütünlük)None
Availability (Erişilebilirlik)Low

Yama durumu bilinmiyor

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

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Weakness Type (CWE & CAPEC)

Similar Vulnerabilities

Get this vulnerability through the API

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CVE-2021-48019 · Vyper before 0.2.9 Incorrect RETURNDATASIZE…