CVE-2020-7699: Express fileupload Prototype Pollution Vulnerability

CRITICAL
Advisory Identifier: GHSA-9wcg-jrwf-8gg7
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CVSS 9.8
CWE-1321 CWE-915
Published
Advisory Summary

CVE-2020-7699 is a CRITICAL (CVSS 9.8) prototype pollution vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting Express fileupload libraries in the npm ecosystem. The issue involves prototype pollution in express-fileupload. Remediation is available by upgrading affected packages to version 1.1.9.

CVE-2020-7699 at a Glance

CVE Identifier CVE-2020-7699
GHSA Identifier GHSA-9wcg-jrwf-8gg7
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product Express fileupload
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-2020-7699

To remediate this vulnerability, upgrade all affected Express fileupload 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-fileupload fixed: 1.1.9 
npm install express-fileupload@1.1.9
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-fileupload

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-7699, inspect your project dependencies using npm:

npm ls express-fileupload

Analyze the terminal output to locate any version of Express fileupload in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.1.9), your application is affected.

Note: The npm ls express-fileupload 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 fileupload, 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

This affects the package express-fileupload before 1.1.8. If the parseNested option is enabled, sending a corrupt HTTP request can lead to denial of service or arbitrary code execution.

CVE-2020-7699 Affected Express fileupload Versions

1 component(s)
Fixed Versions:
1.1.9
Product / Package Ecosystem Affected Versions Fixed Version
express-fileupload
npm/express-fileupload
npm
< 1.1.9
1.1.9

References

NVD — CVE-2020-7699 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-7699
Express fileupload Source Repository REPOSITORY
https://github.com/richardgirges/express-fileupload/issues/236
Express fileupload Source Repository REPOSITORY
https://github.com/richardgirges/express-fileupload/pull/237
Security Fix Commit FIX COMMIT
https://github.com/richardgirges/express-fileupload/commit/db495357d7557ceb5c034de91a7a574bd12f9b9f
Express fileupload Source Repository REPOSITORY
https://github.com/richardgirges/express-fileupload
Express fileupload Security Information SECURITY
https://security.netapp.com/advisory/ntap-20200821-0003
snyk.io/vuln/snyk-js-expres... WEB
https://snyk.io/vuln/SNYK-JS-EXPRESSFILEUPLOAD-595969

Frequently Asked Questions

What is CVE-2020-7699?
CVE-2020-7699 is a security vulnerability in Express fileupload involving Prototype Pollution in express-fileupload under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which Express fileupload versions are affected?
Affected versions include releases prior to 1.1.9 across affected packages: express-fileupload.
What version fixes CVE-2020-7699?
Upgrading to 1.1.9 (or the latest patched release for your respective branch) resolves the vulnerability.
Is express-fileupload affected?
Yes, express-fileupload is affected in releases prior to 1.1.9. Upgrade your dependency to 1.1.9 or later.
What is the CVSS score of CVE-2020-7699?
CVE-2020-7699 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-2020-7699?
CVE-2020-7699 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-2020-7699?
Run the dependency tree command: 'npm ls express-fileupload'. 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-9wcg-jrwf-8gg7",
  "modified" : "2022-05-04T02:19:36Z",
  "published" : "2020-08-05T14:53:16Z",
  "aliases" : [ "CVE-2020-7699" ],
  "summary" : "Prototype Pollution in express-fileupload",
  "details" : "This affects the package express-fileupload before 1.1.8. If the parseNested option is enabled, sending a corrupt HTTP request can lead to denial of service or arbitrary code execution.",
  "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" : "express-fileupload"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.1.9"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-7699"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/richardgirges/express-fileupload/issues/236"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/richardgirges/express-fileupload/pull/237"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/richardgirges/express-fileupload/commit/db495357d7557ceb5c034de91a7a574bd12f9b9f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/richardgirges/express-fileupload"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20200821-0003"
  }, {
    "type" : "WEB",
    "url" : "https://snyk.io/vuln/SNYK-JS-EXPRESSFILEUPLOAD-595969"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321", "CWE-915" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-08-03T21:20:00Z",
    "nvd_published_at" : "2020-07-30T09:15:00Z"
  }
}