CVE-2023-49803: @koa/cors Overly Permissive Origin Policy Vulnerability

HIGH
Advisory Identifier: GHSA-qxrj-hx23-xp82
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CVSS 8.6
CWE-346
Published
Advisory Summary

CVE-2023-49803 is a HIGH (CVSS 8.6) overly permissive origin policy vulnerability (CWE-346: Origin Validation Error) affecting @koa/cors libraries in the npm ecosystem. The issue involves overly permissive origin policy. Remediation is available by upgrading affected packages to version 5.0.0.

CVE-2023-49803 at a Glance

CVE Identifier CVE-2023-49803
GHSA Identifier GHSA-qxrj-hx23-xp82
Severity HIGH
CVSS v3.1 Base Score 8.6
CWE Classification CWE-346: Origin Validation Error
Affected Product @koa/cors
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 8.6

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:C/C:N/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality None (C:N)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2023-49803

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

@koa/cors fixed: 5.0.0 
npm install @koa/cors@5.0.0
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 @koa/cors

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2023-49803, inspect your project dependencies using npm:

npm ls @koa/cors

Analyze the terminal output to locate any version of @koa/cors in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.0.0), your application is affected.

Note: The npm ls @koa/cors 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-346: Origin Validation Error, where the product does not properly verify that the source of data or communication is valid. In @koa/cors, 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

Currently, the middleware operates in a way that if an allowed origin is not provided, it will return an `Access-Control-Allow-Origin` header with the value of the origin from the request. This behavior completely disables one of the most crucial elements of browsers - the Same Origin Policy (SOP), this could cause a very serious security threat to the users of this middleware. If such behavior is expected, for instance, when middleware is used exclusively for prototypes and not for production applications, it should be heavily emphasized in the documentation along with an indication of the risks associated with such behavior, as many users may not be aware of it.

CVE-2023-49803 Affected @koa/cors Versions

1 component(s)
Fixed Versions:
5.0.0
Product / Package Ecosystem Affected Versions Fixed Version
@koa/cors
npm/@koa/cors
npm
< 5.0.0
5.0.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/koajs/cors/security/advisories/GHSA-qxrj-hx23-xp82
NVD — CVE-2023-49803 NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-49803
Security Fix Commit FIX COMMIT
https://github.com/koajs/cors/commit/f31dac99f5355c41e7d4dd3c4a80c5f154941a11
@koa/cors Source Repository REPOSITORY
https://github.com/koajs/cors

Frequently Asked Questions

What is CVE-2023-49803?
CVE-2023-49803 is a security vulnerability in @koa/cors involving Overly permissive origin policy under CWE-346: Origin Validation Error.
Which @koa/cors versions are affected?
Affected versions include releases prior to 5.0.0 across affected packages: @koa/cors.
What version fixes CVE-2023-49803?
Upgrading to 5.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @koa/cors affected?
Yes, @koa/cors is affected in releases prior to 5.0.0. Upgrade your dependency to 5.0.0 or later.
What is the CVSS score of CVE-2023-49803?
CVE-2023-49803 has a CVSS v3.1 base score of 8.6 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N.
What CWE is associated with CVE-2023-49803?
CVE-2023-49803 is classified under CWE-346: Origin Validation Error (The product does not properly verify that the source of data or communication is valid.).
How can I check npm dependencies for CVE-2023-49803?
Run the dependency tree command: 'npm ls @koa/cors'. 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-qxrj-hx23-xp82",
  "modified" : "2023-12-12T00:46:36Z",
  "published" : "2023-12-11T21:46:21Z",
  "aliases" : [ "CVE-2023-49803" ],
  "summary" : "Overly permissive origin policy",
  "details" : "Currently, the middleware operates in a way that if an allowed origin is not provided, it will return an `Access-Control-Allow-Origin` header with the value of the origin from the request. This behavior completely disables one of the most crucial elements of browsers - the Same Origin Policy (SOP), this could cause a very serious security threat to the users of this middleware.\n\nIf such behavior is expected, for instance, when middleware is used exclusively for prototypes and not for production applications, it should be heavily emphasized in the documentation along with an indication of the risks associated with such behavior, as many users may not be aware of it.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@koa/cors"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/koajs/cors/security/advisories/GHSA-qxrj-hx23-xp82"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-49803"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/koajs/cors/commit/f31dac99f5355c41e7d4dd3c4a80c5f154941a11"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/koajs/cors"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-346" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-12-11T21:46:21Z",
    "nvd_published_at" : "2023-12-11T23:15:07Z"
  }
}