CVE-2020-7616: Express mock middleware Improperly Controlled Modification Of Dynamically-Determined Vulnerability

MODERATE
Advisory Identifier: GHSA-v39h-qm32-8gwq
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CVSS 5.3
CWE-1321 CWE-915
Published
Advisory Summary

CVE-2020-7616 is a MODERATE (CVSS 5.3) improperly controlled modification of dynamically-determined vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting Express mock middleware libraries in the npm ecosystem. The issue involves improperly controlled modification of dynamically-determined object attributes in express-mock-middleware. Remediation is available in the latest vendor maintenance releases.

CVE-2020-7616 at a Glance

CVE Identifier CVE-2020-7616
GHSA Identifier GHSA-v39h-qm32-8gwq
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product Express mock middleware
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.3

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:N/I:L/A:N).

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 None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2020-7616

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

express-mock-middleware fixed: Latest secure release 
npm install express-mock-middleware@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: 

npm ls express-mock-middleware

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-7616, inspect your project dependencies using npm:

npm ls express-mock-middleware

Analyze the terminal output to locate any version of Express mock middleware 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: The npm ls express-mock-middleware 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-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'), where the product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. In Express mock middleware, 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

express-mock-middleware through 0.0.6 is vulnerable to Prototype Pollution. Exported functions by the package can be tricked into adding or modifying properties of the `Object.prototype`. Exploitation of this vulnerability requires creation of a new directory where an attack code can be placed which will then be exported by `express-mock-middleware`. As such, this is considered to be a low risk.

CVE-2020-7616 Affected Express mock middleware Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
express-mock-middleware
npm/express-mock-middleware
npm
≤ 0.0.6

References

NVD — CVE-2020-7616 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-7616
Express mock middleware Source Repository REPOSITORY
https://github.com/LingyuCoder/express-mock-middleware/blob/master/lib/index.js#L39
snyk.io/vuln/snyk-js-expres... WEB
https://snyk.io/vuln/SNYK-JS-EXPRESSMOCKMIDDLEWARE-564120

Frequently Asked Questions

What is CVE-2020-7616?
CVE-2020-7616 is a security vulnerability in Express mock middleware involving Improperly Controlled Modification of Dynamically-Determined Object Attributes in express-mock-middleware under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which Express mock middleware versions are affected?
Affected versions include releases prior to current release patches across affected packages: express-mock-middleware.
What version fixes CVE-2020-7616?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is express-mock-middleware affected?
Yes, express-mock-middleware 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-2020-7616?
CVE-2020-7616 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2020-7616?
CVE-2020-7616 is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.).
How can I check npm dependencies for CVE-2020-7616?
Run the dependency tree command: 'npm ls express-mock-middleware'. 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-v39h-qm32-8gwq",
  "modified" : "2021-07-29T15:53:05Z",
  "published" : "2021-12-09T19:57:29Z",
  "aliases" : [ "CVE-2020-7616" ],
  "summary" : "Improperly Controlled Modification of Dynamically-Determined Object Attributes in express-mock-middleware",
  "details" : "express-mock-middleware through 0.0.6 is vulnerable to Prototype Pollution. Exported functions by the package can be tricked into adding or modifying properties of the `Object.prototype`. Exploitation of this vulnerability requires creation of a new directory where an attack code can be placed which will then be exported by `express-mock-middleware`. As such, this is considered to be a low risk.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "express-mock-middleware"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "0.0.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-7616"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/LingyuCoder/express-mock-middleware/blob/master/lib/index.js#L39"
  }, {
    "type" : "WEB",
    "url" : "https://snyk.io/vuln/SNYK-JS-EXPRESSMOCKMIDDLEWARE-564120"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321", "CWE-915" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-25T17:28:15Z",
    "nvd_published_at" : "2020-04-07T14:15:00Z"
  }
}