CVE-2020-35880: Bigint Unsoundness Vulnerability

CRITICAL
Advisory Identifier: GHSA-wgx2-6432-j3fw
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CVSS 9.8
CWE-704
Published
Advisory Summary

CVE-2020-35880 is a CRITICAL (CVSS 9.8) unsoundness vulnerability (CWE-704: Incorrect Type Conversion or Cast) affecting Bigint libraries in the crates.io ecosystem. The issue involves unsoundness in bigint. Remediation is available in the latest vendor maintenance releases.

CVE-2020-35880 at a Glance

CVE Identifier CVE-2020-35880
GHSA Identifier GHSA-wgx2-6432-j3fw
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-704: Incorrect Type Conversion or Cast
Affected Product Bigint
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 9.8

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

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
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-2020-35880

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

bigint fixed: Latest secure release 
Upgrade bigint to Latest secure release
Verify Direct and Transitive Dependencies

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

inspect dependencies for bigint

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-35880, inspect your project dependencies for Bigint:

inspect dependencies for bigint

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

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-704: Incorrect Type Conversion or Cast, where the product does not correctly convert an object, resource, or structure from one type to a different type. In Bigint, 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

An issue was discovered in the bigint crate through 2020-05-07 for Rust. It allows a soundness violation.

CVE-2020-35880 Affected Bigint Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
bigint
 crates.io
≤ 4.4.3

References

NVD — CVE-2020-35880 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-35880
Bigint Source Repository REPOSITORY
https://github.com/rustsec/advisory-db/pull/290
Security Fix Commit FIX COMMIT
https://github.com/paritytech/bigint/commit/7e71521a61b009afc94c91135353102658550d42
Bigint Source Repository REPOSITORY
https://github.com/paritytech/bigint
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2020-0025.html

Frequently Asked Questions

What is CVE-2020-35880?
CVE-2020-35880 is a security vulnerability in Bigint involving Unsoundness in bigint under CWE-704: Incorrect Type Conversion or Cast.
Which Bigint versions are affected?
Affected versions include releases prior to current release patches across affected packages: bigint.
What version fixes CVE-2020-35880?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is bigint affected?
Yes, bigint is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2020-35880?
CVE-2020-35880 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2020-35880?
CVE-2020-35880 is classified under CWE-704: Incorrect Type Conversion or Cast (The product does not correctly convert an object, resource, or structure from one type to a different type.).
How can I check crates.io dependencies for CVE-2020-35880?
Run the dependency tree command: 'inspect dependencies for bigint'. 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-wgx2-6432-j3fw",
  "modified" : "2021-08-19T21:07:53Z",
  "published" : "2021-08-25T20:48:04Z",
  "aliases" : [ "CVE-2020-35880" ],
  "summary" : "Unsoundness in bigint",
  "details" : "An issue was discovered in the bigint crate through 2020-05-07 for Rust. It allows a soundness violation.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "bigint"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "4.4.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-35880"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rustsec/advisory-db/pull/290"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/paritytech/bigint/commit/7e71521a61b009afc94c91135353102658550d42"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/paritytech/bigint"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2020-0025.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-704" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-19T21:07:53Z",
    "nvd_published_at" : null
  }
}