CVE-2021-24037: Hermes engine Use After Free Vulnerability

CRITICAL
Advisory Identifier: GHSA-mph8-6787-r8hw
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CVSS 9.8
CWE-416
Published
Advisory Summary

CVE-2021-24037 is a CRITICAL (CVSS 9.8) use after free vulnerability (CWE-416: Use After Free) affecting Hermes engine libraries in the npm ecosystem. The issue involves use after free in hermes. Remediation is available by upgrading affected packages to version 0.8.0.

CVE-2021-24037 at a Glance

CVE Identifier CVE-2021-24037
GHSA Identifier GHSA-mph8-6787-r8hw
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-416: Use After Free
Affected Product Hermes engine
Package Ecosystem npm
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-2021-24037

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

hermes-engine fixed: 0.8.0 
npm install hermes-engine@0.8.0
Verify Direct and Transitive Dependencies

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

npm ls hermes-engine

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2021-24037, inspect your project dependencies using npm:

npm ls hermes-engine

Analyze the terminal output to locate any version of Hermes engine in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.8.0), your application is affected.

Note: The npm ls hermes-engine command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-416: Use After Free, where the product reuses or references memory after it has been freed. at some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. In Hermes engine, 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

A use after free in hermes, while emitting certain error messages, prior to commit d86e185e485b6330216dee8e854455c694e3a36e allows attackers to potentially execute arbitrary code via crafted JavaScript. Note that this is only exploitable if the application using Hermes permits evaluation of untrusted JavaScript. Hence, most React Native applications are not affected.

CVE-2021-24037 Affected Hermes engine Versions

1 component(s)
Fixed Versions:
0.8.0
Product / Package Ecosystem Affected Versions Fixed Version
hermes-engine
npm/hermes-engine
npm
< 0.8.0
0.8.0

References

NVD — CVE-2021-24037 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-24037
Security Fix Commit FIX COMMIT
https://github.com/facebook/hermes/commit/d86e185e485b6330216dee8e854455c694e3a36e
Hermes engine Source Repository REPOSITORY
https://github.com/facebook/hermes
Hermes engine Security Information SECURITY
https://www.facebook.com/security/advisories/CVE-2021-24037

Frequently Asked Questions

What is CVE-2021-24037?
CVE-2021-24037 is a security vulnerability in Hermes engine involving Use After Free in Hermes under CWE-416: Use After Free.
Which Hermes engine versions are affected?
Affected versions include releases prior to 0.8.0 across affected packages: hermes-engine.
What version fixes CVE-2021-24037?
Upgrading to 0.8.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is hermes-engine affected?
Yes, hermes-engine is affected in releases prior to 0.8.0. Upgrade your dependency to 0.8.0 or later.
What is the CVSS score of CVE-2021-24037?
CVE-2021-24037 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-2021-24037?
CVE-2021-24037 is classified under CWE-416: Use After Free (The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.).
How can I check npm dependencies for CVE-2021-24037?
Run the dependency tree command: 'npm ls hermes-engine'. 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-mph8-6787-r8hw",
  "modified" : "2022-06-22T18:20:01Z",
  "published" : "2022-05-24T19:05:34Z",
  "aliases" : [ "CVE-2021-24037" ],
  "summary" : "Use After Free in Hermes",
  "details" : "A use after free in hermes, while emitting certain error messages, prior to commit d86e185e485b6330216dee8e854455c694e3a36e allows attackers to potentially execute arbitrary code via crafted JavaScript. Note that this is only exploitable if the application using Hermes permits evaluation of untrusted JavaScript. Hence, most React Native applications are not affected.",
  "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" : "npm",
      "name" : "hermes-engine"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.8.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.7.2"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-24037"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/facebook/hermes/commit/d86e185e485b6330216dee8e854455c694e3a36e"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/facebook/hermes"
  }, {
    "type" : "WEB",
    "url" : "https://www.facebook.com/security/advisories/CVE-2021-24037"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-416" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-06-22T18:20:01Z",
    "nvd_published_at" : "2021-06-15T22:15:00Z"
  }
}