CVE-2020-7767: Express validators Regular Expression Deinal Of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-cf2x-rqc8-grfq
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CVSS 5.3
CWE-400
Published
Advisory Summary

CVE-2020-7767 is a MODERATE (CVSS 5.3) regular expression deinal of service vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Express validators libraries in the npm ecosystem. The issue involves regular expression deinal of service in express-validators. Remediation is available in the latest vendor maintenance releases.

CVE-2020-7767 at a Glance

CVE Identifier CVE-2020-7767
GHSA Identifier GHSA-cf2x-rqc8-grfq
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Express validators
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:N/A:L).

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

How to Fix CVE-2020-7767

To remediate this vulnerability, upgrade all affected Express validators 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-validators fixed: Latest secure release 
npm install express-validators@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-validators

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-7767, inspect your project dependencies using npm:

npm ls express-validators

Analyze the terminal output to locate any version of Express validators 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-validators 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-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In Express validators, 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

All versions of package express-validators are vulnerable to Regular Expression Denial of Service (ReDoS) when validating specifically-crafted invalid urls.

CVE-2020-7767 Affected Express validators Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
express-validators
npm/express-validators
npm
≤ 1.0.4

References

NVD — CVE-2020-7767 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-7767
snyk.io/vuln/snyk-js-expres... WEB
https://snyk.io/vuln/SNYK-JS-EXPRESSVALIDATORS-1017404

Frequently Asked Questions

What is CVE-2020-7767?
CVE-2020-7767 is a security vulnerability in Express validators involving Regular expression deinal of service in express-validators under CWE-400: Uncontrolled Resource Consumption.
Which Express validators versions are affected?
Affected versions include releases prior to current release patches across affected packages: express-validators.
What version fixes CVE-2020-7767?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is express-validators affected?
Yes, express-validators 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-2020-7767?
CVE-2020-7767 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:N/A:L.
What CWE is associated with CVE-2020-7767?
CVE-2020-7767 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check npm dependencies for CVE-2020-7767?
Run the dependency tree command: 'npm ls express-validators'. 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-cf2x-rqc8-grfq",
  "modified" : "2021-04-19T22:44:18Z",
  "published" : "2021-05-10T19:16:27Z",
  "aliases" : [ "CVE-2020-7767" ],
  "summary" : "Regular expression deinal of service in express-validators",
  "details" : "All versions of package express-validators are vulnerable to Regular Expression Denial of Service (ReDoS) when validating specifically-crafted invalid urls.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "express-validators"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.0.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-7767"
  }, {
    "type" : "WEB",
    "url" : "https://snyk.io/vuln/SNYK-JS-EXPRESSVALIDATORS-1017404"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-04-19T22:44:18Z",
    "nvd_published_at" : "2020-11-11T11:15:00Z"
  }
}