CVE-2020-1911: Hermes engine Remote Code Execution Vulnerability

CRITICAL
Advisory Identifier: GHSA-f5x2-xv93-4p23
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CVSS 9.8
CWE-843
Published
Advisory Summary

CVE-2020-1911 is a CRITICAL (CVSS 9.8) remote code execution vulnerability (CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')) affecting Hermes engine libraries in the npm ecosystem. The issue involves access of resource using incompatible type in facebook hermes. Remediation is available by upgrading affected packages to version 0.5.2.

CVE-2020-1911 at a Glance

CVE Identifier CVE-2020-1911
GHSA Identifier GHSA-f5x2-xv93-4p23
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')
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-2020-1911

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: 0.5.2 
npm install hermes-engine@0.5.2
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-2020-1911, 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 0.5.2), 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-843: Access of Resource Using Incompatible Type ('Type Confusion'), where the product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type. 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 type confusion vulnerability when resolving properties of JavaScript objects with specially-crafted prototype chains in Facebook Hermes prior to commit fe52854cdf6725c2eaa9e125995da76e6ceb27da 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-2020-1911 Affected Hermes engine Versions

1 component(s)
Fixed Versions:
0.5.2
Product / Package Ecosystem Affected Versions Fixed Version
hermes-engine
npm/hermes-engine
npm
< 0.5.2
0.5.2

References

NVD — CVE-2020-1911 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-1911
Security Fix Commit FIX COMMIT
https://github.com/facebook/hermes/commit/fe52854cdf6725c2eaa9e125995da76e6ceb27da
Hermes engine Security Information SECURITY
https://www.facebook.com/security/advisories/cve-2020-1911

Frequently Asked Questions

What is CVE-2020-1911?
CVE-2020-1911 is a security vulnerability in Hermes engine involving Access of Resource Using Incompatible Type in Facebook Hermes under CWE-843: Access of Resource Using Incompatible Type ('Type Confusion').
Which Hermes engine versions are affected?
Affected versions include releases prior to 0.5.2 across affected packages: hermes-engine.
What version fixes CVE-2020-1911?
Upgrading to 0.5.2 (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 0.5.2. Upgrade your dependency to 0.5.2 or later.
What is the CVSS score of CVE-2020-1911?
CVE-2020-1911 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-2020-1911?
CVE-2020-1911 is classified under CWE-843: Access of Resource Using Incompatible Type ('Type Confusion') (The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.).
How can I check npm dependencies for CVE-2020-1911?
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-f5x2-xv93-4p23",
  "modified" : "2022-06-24T01:24:06Z",
  "published" : "2022-05-24T17:27:24Z",
  "aliases" : [ "CVE-2020-1911" ],
  "summary" : "Access of Resource Using Incompatible Type in Facebook Hermes",
  "details" : "A type confusion vulnerability when resolving properties of JavaScript objects with specially-crafted prototype chains in Facebook Hermes prior to commit fe52854cdf6725c2eaa9e125995da76e6ceb27da 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" : "0.5.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.4.3"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-1911"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/facebook/hermes/commit/fe52854cdf6725c2eaa9e125995da76e6ceb27da"
  }, {
    "type" : "WEB",
    "url" : "https://www.facebook.com/security/advisories/cve-2020-1911"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-843" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-06-24T01:24:06Z",
    "nvd_published_at" : "2020-09-04T03:15:00Z"
  }
}