CVE-2021-36788: Yoast seo for typo3/yoast seo Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-28w5-j8xj-2xwc
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CVSS 5.4
CWE-79
Published
Advisory Summary

CVE-2021-36788 is a MODERATE (CVSS 5.4) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Yoast seo for typo3/yoast seo libraries in the Packagist ecosystem. The issue involves cross-site scripting in the yoast_seo typo3 extension. Remediation is available by upgrading affected packages to version 7.2.3.

CVE-2021-36788 at a Glance

CVE Identifier CVE-2021-36788
GHSA Identifier GHSA-28w5-j8xj-2xwc
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Yoast seo for typo3/yoast seo
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 5.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N).

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

How to Fix CVE-2021-36788

To remediate this vulnerability, upgrade all affected Yoast seo for typo3/yoast seo dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

yoast-seo-for-typo3/yoast_seo fixed: 7.2.3 
Upgrade yoast-seo-for-typo3/yoast_seo to 7.2.3
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 yoast-seo-for-typo3/yoast_seo

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-36788, inspect your project dependencies for Yoast seo for typo3/yoast seo:

inspect dependencies for yoast-seo-for-typo3/yoast_seo

Analyze the terminal output to locate any version of Yoast seo for typo3/yoast seo in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 7.2.3), 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-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Yoast seo for typo3/yoast seo, 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

The extension fails to properly encode user input for output in HTML context. A TYPO3 backend user account is required to exploit the vulnerability.

CVE-2021-36788 Affected Yoast seo for typo3/yoast seo Versions

1 component(s)
Fixed Versions:
7.2.3
Product / Package Ecosystem Affected Versions Fixed Version
yoast-seo-for-typo3/yoast_seo
 Packagist
< 7.2.3
7.2.3

References

NVD — CVE-2021-36788 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-36788
Security Fix Commit FIX COMMIT
https://github.com/Yoast/Yoast-SEO-for-TYPO3/commit/a8278dae97dce8cd0722d38f7f5a30b563668590
Yoast seo for typo3/yoast seo Source Repository REPOSITORY
https://github.com/Yoast/Yoast-SEO-for-TYPO3
Yoast seo for typo3/yoast seo Security Information SECURITY
https://typo3.org/security/advisory/typo3-ext-sa-2021-012

Frequently Asked Questions

What is CVE-2021-36788?
CVE-2021-36788 is a security vulnerability in Yoast seo for typo3/yoast seo involving Cross-site Scripting in the yoast_seo TYPO3 extension under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Yoast seo for typo3/yoast seo versions are affected?
Affected versions include releases prior to 7.2.3 across affected packages: yoast-seo-for-typo3/yoast_seo.
What version fixes CVE-2021-36788?
Upgrading to 7.2.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is yoast-seo-for-typo3/yoast_seo affected?
Yes, yoast-seo-for-typo3/yoast_seo is affected in releases prior to 7.2.3. Upgrade your dependency to 7.2.3 or later.
What is the CVSS score of CVE-2021-36788?
CVE-2021-36788 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2021-36788?
CVE-2021-36788 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check Packagist dependencies for CVE-2021-36788?
Run the dependency tree command: 'inspect dependencies for yoast-seo-for-typo3/yoast_seo'. 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-28w5-j8xj-2xwc",
  "modified" : "2021-08-30T18:43:25Z",
  "published" : "2021-09-01T18:36:44Z",
  "aliases" : [ "CVE-2021-36788" ],
  "summary" : "Cross-site Scripting in the yoast_seo TYPO3 extension",
  "details" : "The extension fails to properly encode user input for output in HTML context. A TYPO3 backend user account is required to exploit the vulnerability.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "yoast-seo-for-typo3/yoast_seo"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "7.2.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-36788"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Yoast/Yoast-SEO-for-TYPO3/commit/a8278dae97dce8cd0722d38f7f5a30b563668590"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Yoast/Yoast-SEO-for-TYPO3"
  }, {
    "type" : "WEB",
    "url" : "https://typo3.org/security/advisory/typo3-ext-sa-2021-012"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-30T18:43:25Z",
    "nvd_published_at" : "2021-08-13T17:15:00Z"
  }
}