CVE-2021-3734: Yourls/yourls Improper Restriction Of Rendered UI Vulnerability

MODERATE

Advisory Identifier: GHSA-r6g8-jmj9-g945

CVSS 6.5

Published 2021-08-30

Advisory Summary

CVE-2021-3734 is a MODERATE (CVSS 6.5) improper restriction of rendered ui vulnerability (CWE-1021: Improper Restriction of Rendered UI Layers or Frames) affecting Yourls/yourls libraries in the Packagist ecosystem. The issue involves improper restriction of rendered ui layers or frames in yourls. Remediation is available in the latest vendor maintenance releases.

CVE-2021-3734 at a Glance

CVE Identifier CVE-2021-3734

GHSA Identifier GHSA-r6g8-jmj9-g945

Severity MODERATE

CVSS v3.1 Base Score 6.5

CWE Classification CWE-1021: Improper Restriction of Rendered UI Layers or Frames

Affected Product Yourls/yourls

Package Ecosystem Packagist

Published Date 2021-08-30

Last Updated 2021-08-27

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/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 Unchanged (S:U)

Confidentiality Low (C:L)

Integrity Low (I:L)

Availability None (A:N)

How to Fix CVE-2021-3734

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

yourls/yourls fixed: Latest secure release

Upgrade yourls/yourls to 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:

inspect dependencies for yourls/yourls

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-3734, inspect your project dependencies for Yourls/yourls:

inspect dependencies for yourls/yourls

Analyze the terminal output to locate any version of Yourls/yourls 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: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-1021: Improper Restriction of Rendered UI Layers or Frames, where the web application does not restrict or incorrectly restricts frame objects or ui layers that belong to another application or domain. In Yourls/yourls, 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

yourls is vulnerable to Improper Restriction of Rendered UI Layers or Frames

CVE-2021-3734 Affected Yourls/yourls Versions

1 component(s)

Product / Package	Ecosystem	Affected Versions	Fixed Version
yourls/yourls	Packagist	≤ 1.8.1

References

NVD — CVE-2021-3734 NVD

https://nvd.nist.gov/vuln/detail/CVE-2021-3734

Security Fix Commit FIX COMMIT

https://github.com/yourls/yourls/commit/0a70acdcfb5fcbc63dbc5750018d608288eba3fe

Yourls/yourls Source Repository REPOSITORY

https://github.com/yourls/yourls

huntr.dev/bounties/dd2e2dbe-e... WEB

https://huntr.dev/bounties/dd2e2dbe-efe5-49ec-be11-7a7e7c41debd

Frequently Asked Questions

What is CVE-2021-3734?

CVE-2021-3734 is a security vulnerability in Yourls/yourls involving Improper Restriction of Rendered UI Layers or Frames in yourls under CWE-1021: Improper Restriction of Rendered UI Layers or Frames.

Which Yourls/yourls versions are affected?

Affected versions include releases prior to current release patches across affected packages: yourls/yourls.

What version fixes CVE-2021-3734?

Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.

Is yourls/yourls affected?

Yes, yourls/yourls 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-2021-3734?

CVE-2021-3734 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.

What CWE is associated with CVE-2021-3734?

CVE-2021-3734 is classified under CWE-1021: Improper Restriction of Rendered UI Layers or Frames (The web application does not restrict or incorrectly restricts frame objects or UI layers that belong to another application or domain.).

How can I check Packagist dependencies for CVE-2021-3734?

Run the dependency tree command: 'inspect dependencies for yourls/yourls'. 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-r6g8-jmj9-g945",
  "modified" : "2021-08-27T12:54:01Z",
  "published" : "2021-08-30T16:22:16Z",
  "aliases" : [ "CVE-2021-3734" ],
  "summary" : "Improper Restriction of Rendered UI Layers or Frames in yourls",
  "details" : "yourls is vulnerable to Improper Restriction of Rendered UI Layers or Frames",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "yourls/yourls"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.8.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-3734"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/yourls/yourls/commit/0a70acdcfb5fcbc63dbc5750018d608288eba3fe"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/yourls/yourls"
  }, {
    "type" : "WEB",
    "url" : "https://huntr.dev/bounties/dd2e2dbe-efe5-49ec-be11-7a7e7c41debd"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1021", "CWE-352" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-27T12:54:01Z",
    "nvd_published_at" : "2021-08-26T13:15:00Z"
  }
}

CVSS V3

6.5 MODERATE