CVE-2020-26938: Oauth2 server Oauth2-server Through 3.1.1 Vulnerable To Vulnerability

HIGH
Advisory Identifier: GHSA-4rg6-fm25-gc34
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CVSS 7.2
CWE-601
Published
Advisory Summary

CVE-2020-26938 is a HIGH (CVSS 7.2) oauth2-server through 3.1.1 vulnerable to vulnerability (CWE-601: URL Redirection to Untrusted Site ('Open Redirect')) affecting Oauth2 server libraries in the npm ecosystem. The issue involves oauth2-server through 3.1.1 vulnerable to open redirect. Remediation is available in the latest vendor maintenance releases.

CVE-2020-26938 at a Glance

CVE Identifier CVE-2020-26938
GHSA Identifier GHSA-4rg6-fm25-gc34
Severity HIGH
CVSS v3.1 Base Score 7.2
CWE Classification CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
Affected Product Oauth2 server
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.2

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:L/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 Changed (S:C)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2020-26938

To remediate this vulnerability, upgrade all affected Oauth2 server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

oauth2-server fixed: Latest secure release 
npm install oauth2-server@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 oauth2-server

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-26938, inspect your project dependencies using npm:

npm ls oauth2-server

Analyze the terminal output to locate any version of Oauth2 server 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 oauth2-server 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-601: URL Redirection to Untrusted Site ('Open Redirect'), where the web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect. In Oauth2 server, 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

In oauth2-server (aka node-oauth2-server) through 3.1.1, the value of the `redirect_uri` parameter received during the authorization and token request is checked against an incorrect URI pattern (`[a-zA-Z][a-zA-Z0-9+.-]+:`) before making a redirection. This allows a malicious client to pass an XSS payload through the redirect_uri parameter while making an authorization request. NOTE: this vulnerability is similar to CVE-2020-7741.

CVE-2020-26938 Affected Oauth2 server Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
oauth2-server
npm/oauth2-server
npm
≤ 3.1.1

References

NVD — CVE-2020-26938 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-26938
Oauth2 server Source Repository REPOSITORY
https://github.com/oauthjs/node-oauth2-server/issues/637
Oauth2 server Source Repository REPOSITORY
https://github.com/oauthjs/node-oauth2-server
Oauth2 server Source Repository REPOSITORY
https://github.com/oauthjs/node-oauth2-server/blob/91d2cbe70a0eddc53d72def96864e2de0fd41703/lib/grant-types/authorization-code-grant-type.js#L143
Oauth2 server Source Repository REPOSITORY
https://github.com/oauthjs/node-oauth2-server/blob/91d2cbe70a0eddc53d72def96864e2de0fd41703/lib/validator/is.js#L12
tools.ietf.org/html/rfc3986 WEB
https://tools.ietf.org/html/rfc3986#section-3
tools.ietf.org/html/rfc6749 WEB
https://tools.ietf.org/html/rfc6749#section-3.1.2

Frequently Asked Questions

What is CVE-2020-26938?
CVE-2020-26938 is a security vulnerability in Oauth2 server involving oauth2-server through 3.1.1 vulnerable to Open Redirect under CWE-601: URL Redirection to Untrusted Site ('Open Redirect').
Which Oauth2 server versions are affected?
Affected versions include releases prior to current release patches across affected packages: oauth2-server.
What version fixes CVE-2020-26938?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is oauth2-server affected?
Yes, oauth2-server 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-2020-26938?
CVE-2020-26938 has a CVSS v3.1 base score of 7.2 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2020-26938?
CVE-2020-26938 is classified under CWE-601: URL Redirection to Untrusted Site ('Open Redirect') (The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.).
How can I check npm dependencies for CVE-2020-26938?
Run the dependency tree command: 'npm ls oauth2-server'. 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-4rg6-fm25-gc34",
  "modified" : "2022-09-16T19:36:13Z",
  "published" : "2022-08-30T00:00:26Z",
  "aliases" : [ "CVE-2020-26938" ],
  "summary" : "oauth2-server through 3.1.1 vulnerable to Open Redirect",
  "details" : "In oauth2-server (aka node-oauth2-server) through 3.1.1, the value of the `redirect_uri` parameter received during the authorization and token request is checked against an incorrect URI pattern (`[a-zA-Z][a-zA-Z0-9+.-]+:`) before making a redirection. This allows a malicious client to pass an XSS payload through the redirect_uri parameter while making an authorization request. NOTE: this vulnerability is similar to CVE-2020-7741.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "oauth2-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "3.1.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-26938"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/oauthjs/node-oauth2-server/issues/637"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/oauthjs/node-oauth2-server"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/oauthjs/node-oauth2-server/blob/91d2cbe70a0eddc53d72def96864e2de0fd41703/lib/grant-types/authorization-code-grant-type.js#L143"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/oauthjs/node-oauth2-server/blob/91d2cbe70a0eddc53d72def96864e2de0fd41703/lib/validator/is.js#L12"
  }, {
    "type" : "WEB",
    "url" : "https://tools.ietf.org/html/rfc3986#section-3"
  }, {
    "type" : "WEB",
    "url" : "https://tools.ietf.org/html/rfc6749#section-3.1.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-601" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-09-16T19:36:13Z",
    "nvd_published_at" : "2022-08-29T21:15:00Z"
  }
}