CVE-2021-41121: Vyper Memory Corruption When Returning A Vulnerability

HIGH
Advisory Identifier: GHSA-xv8x-pr4h-73jv
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CVSS 7.5
CWE-119
Published
Advisory Summary

CVE-2021-41121 is a HIGH (CVSS 7.5) memory corruption when returning a vulnerability (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer) affecting Vyper libraries in the PyPI ecosystem. The issue involves memory corruption when returning a literal struct with a private call inside of it. Remediation is available by upgrading affected packages to version 0.3.0.

CVE-2021-41121 at a Glance

CVE Identifier CVE-2021-41121
GHSA Identifier GHSA-xv8x-pr4h-73jv
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
Affected Product Vyper
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2021-41121

To remediate this vulnerability, upgrade all affected Vyper dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

vyper fixed: 0.3.0 
pip install vyper>=0.3.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show vyper

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2021-41121, inspect your installed packages using pip:

pip show vyper

Analyze the terminal output to locate any version of Vyper in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.3.0), your application is affected.

Note: The pip show vyper command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer, where the product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. this may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data. In Vyper, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact When performing a function call inside a literal struct, there is a memory corruption issue that occurs because of an incorrect pointer to the the top of the stack. ### Patches 0.3.0 / #2447 *

CVE-2021-41121 Affected Vyper Versions

1 component(s)
Fixed Versions:
0.3.0
Product / Package Ecosystem Affected Versions Fixed Version
vyper
pypi/vyper
PyPI
< 0.3.0
0.3.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/vyperlang/vyper/security/advisories/GHSA-xv8x-pr4h-73jv
NVD — CVE-2021-41121 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-41121
Vyper Source Repository REPOSITORY
https://github.com/vyperlang/vyper/pull/2447
Vyper Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2021-365.yaml
Vyper Source Repository REPOSITORY
https://github.com/vyperlang/vyper

Frequently Asked Questions

What is CVE-2021-41121?
CVE-2021-41121 is a security vulnerability in Vyper involving Memory corruption when returning a literal struct with a private call inside of it under CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer.
Which Vyper versions are affected?
Affected versions include releases prior to 0.3.0 across affected packages: vyper.
What version fixes CVE-2021-41121?
Upgrading to 0.3.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is vyper affected?
Yes, vyper is affected in releases prior to 0.3.0. Upgrade your dependency to 0.3.0 or later.
What is the CVSS score of CVE-2021-41121?
CVE-2021-41121 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-41121?
CVE-2021-41121 is classified under CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer (The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.).
How can I check PyPI dependencies for CVE-2021-41121?
Run the dependency tree command: 'pip show vyper'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xv8x-pr4h-73jv",
  "modified" : "2024-11-18T22:44:23Z",
  "published" : "2021-10-12T15:59:29Z",
  "aliases" : [ "CVE-2021-41121" ],
  "summary" : "Memory corruption when returning a literal struct with a private call inside of it",
  "details" : "### Impact\n\nWhen performing a function call inside a literal struct, there is a memory corruption issue that occurs because of an incorrect pointer to the the top of the stack.\n\n### Patches\n0.3.0 / #2447\n\n*",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "vyper"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.3.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/vyperlang/vyper/security/advisories/GHSA-xv8x-pr4h-73jv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-41121"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vyperlang/vyper/pull/2447"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/vyper/PYSEC-2021-365.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/vyperlang/vyper"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-119" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-10-06T17:47:24Z",
    "nvd_published_at" : "2021-10-06T18:15:00Z"
  }
}