CVE-2021-29940: Through Double Free Vulnerability

CRITICAL
Advisory Identifier: GHSA-5hpj-m323-cphm
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CVSS 9.8
CWE-415
Published
Advisory Summary

CVE-2021-29940 is a CRITICAL (CVSS 9.8) double free vulnerability (CWE-415: Double Free) affecting Through libraries in the crates.io ecosystem. The issue involves double free in through. Remediation is available in the latest vendor maintenance releases.

CVE-2021-29940 at a Glance

CVE Identifier CVE-2021-29940
GHSA Identifier GHSA-5hpj-m323-cphm
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-415: Double Free
Affected Product Through
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-2021-29940

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

through fixed: Latest secure release 
Upgrade through 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 through

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-29940, inspect your project dependencies for Through:

inspect dependencies for through

Analyze the terminal output to locate any version of Through 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-415: Double Free, where the product calls free() twice on the same memory address. In Through, 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 through crate through 2021-02-18 for Rust. There is a double free (in through and through_and) upon a panic of the map function.

CVE-2021-29940 Affected Through Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
through
 crates.io
≤ 0.1.0

References

NVD — CVE-2021-29940 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-29940
Through Source Repository REPOSITORY
https://github.com/gretchenfrage/through/issues/1
Through Source Repository REPOSITORY
https://github.com/gretchenfrage/through
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2021-0049.html

Frequently Asked Questions

What is CVE-2021-29940?
CVE-2021-29940 is a security vulnerability in Through involving Double free in through under CWE-415: Double Free.
Which Through versions are affected?
Affected versions include releases prior to current release patches across affected packages: through.
What version fixes CVE-2021-29940?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is through affected?
Yes, through 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-2021-29940?
CVE-2021-29940 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-2021-29940?
CVE-2021-29940 is classified under CWE-415: Double Free (The product calls free() twice on the same memory address.).
How can I check crates.io dependencies for CVE-2021-29940?
Run the dependency tree command: 'inspect dependencies for through'. 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-5hpj-m323-cphm",
  "modified" : "2021-08-19T17:15:33Z",
  "published" : "2021-08-25T20:54:12Z",
  "aliases" : [ "CVE-2021-29940" ],
  "summary" : "Double free in through",
  "details" : "An issue was discovered in the through crate through 2021-02-18 for Rust. There is a double free (in through and through_and) upon a panic of the map function.",
  "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" : "through"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "0.1.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-29940"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gretchenfrage/through/issues/1"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/gretchenfrage/through"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2021-0049.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-415" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-19T17:15:33Z",
    "nvd_published_at" : null
  }
}