CVE-2021-21370: Typo3/cms Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-x7hc-x7fm-f7qh
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CVSS 5.4
CWE-79
Published
Advisory Summary

CVE-2021-21370 is a MODERATE (CVSS 5.4) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Typo3/cms libraries in the Packagist ecosystem. The issue involves cross-site scripting in content preview (ctype menu). Remediation is available by upgrading affected packages to version 11.1.1, 7.6.51, 8.7.40, 9.5.25, 10.4.14.

CVE-2021-21370 at a Glance

CVE Identifier CVE-2021-21370
GHSA Identifier GHSA-x7hc-x7fm-f7qh
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 Typo3/cms
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-2021-21370

To remediate this vulnerability, upgrade all affected Typo3/cms dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

typo3/cms fixed: 11.1.1 
Upgrade typo3/cms to 11.1.1
typo3/cms-backend fixed: 7.6.51 
Upgrade typo3/cms-backend to 7.6.51
typo3/cms-backend fixed: 8.7.40 
Upgrade typo3/cms-backend to 8.7.40
typo3/cms-backend fixed: 9.5.25 
Upgrade typo3/cms-backend to 9.5.25
typo3/cms-backend fixed: 10.4.14 
Upgrade typo3/cms-backend to 10.4.14
typo3/cms-backend fixed: 11.1.1 
Upgrade typo3/cms-backend to 11.1.1
typo3/cms-core fixed: 10.4.14 
Upgrade typo3/cms-core to 10.4.14
typo3/cms-core fixed: 11.1.1 
Upgrade typo3/cms-core to 11.1.1
typo3/cms-core fixed: 9.5.25 
Upgrade typo3/cms-core to 9.5.25
typo3/cms fixed: 10.4.14 
Upgrade typo3/cms to 10.4.14
typo3/cms fixed: 9.5.25 
Upgrade typo3/cms to 9.5.25
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 typo3/cms

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-21370, inspect your project dependencies for Typo3/cms:

inspect dependencies for typo3/cms

Analyze the terminal output to locate any version of Typo3/cms in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 11.1.1), 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 Typo3/cms, 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

### Problem It has been discovered that content elements of type _menu_ are vulnerable to cross-site scripting when their referenced items get previewed in the page module. A valid backend user account is needed to exploit this vulnerability. ### Solution Update to TYPO3 versions 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1 that fix the problem described. ### Credits Thanks to TYPO3 contributor Oliver Bartsch who reported and fixed the issue. ### References * [TYPO3-CORE-SA-2021-008](https://typo3.org/security/advisory/typo3-core-sa-2021-008)

CVE-2021-21370 Affected Typo3/cms Versions

11 component(s)
Fixed Versions:
11.1.17.6.518.7.409.5.2510.4.14
Product / Package Ecosystem Affected Versions Fixed Version
typo3/cms
 Packagist
≥ 11.0.0
< 11.1.1
11.1.1
typo3/cms-backend
 Packagist
≥ 7.0.0
< 7.6.51
7.6.51
typo3/cms-backend
 Packagist
≥ 8.0.0
< 8.7.40
8.7.40
typo3/cms-backend
 Packagist
≥ 9.0.0
< 9.5.25
9.5.25
typo3/cms-backend
 Packagist
≥ 10.0.0
< 10.4.14
10.4.14
typo3/cms-backend
 Packagist
≥ 11.0.0
< 11.1.1
11.1.1
typo3/cms-core
 Packagist
≥ 10.0.0
< 10.4.14
10.4.14
typo3/cms-core
 Packagist
≥ 11.0.0
< 11.1.1
11.1.1
typo3/cms-core
 Packagist
≥ 9.0.0
< 9.5.25
9.5.25
typo3/cms
 Packagist
≥ 10.0.0
< 10.4.14
10.4.14
typo3/cms
 Packagist
≥ 9.0.0
< 9.5.25
9.5.25

References

GitHub Advisory / Wiki ADVISORY
https://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-x7hc-x7fm-f7qh
NVD — CVE-2021-21370 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-21370
Typo3/cms Source Repository REPOSITORY
https://github.com/FriendsOfPHP/security-advisories/blob/master/typo3/cms-core/CVE-2021-21370.yaml
Typo3/cms Source Repository REPOSITORY
https://github.com/FriendsOfPHP/security-advisories/blob/master/typo3/cms/CVE-2021-21370.yaml
packagist.org/packages/typo3/cms-... WEB
https://packagist.org/packages/typo3/cms-backend
Typo3/cms Security Information SECURITY
https://typo3.org/security/advisory/typo3-core-sa-2021-008

Frequently Asked Questions

What is CVE-2021-21370?
CVE-2021-21370 is a security vulnerability in Typo3/cms involving Cross-Site Scripting in Content Preview (CType menu) under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Typo3/cms versions are affected?
Affected versions include releases prior to 11.1.1, 7.6.51, 8.7.40, 9.5.25, 10.4.14 across affected packages: typo3/cms, typo3/cms-backend, typo3/cms-core.
What version fixes CVE-2021-21370?
Upgrading to 11.1.1, 7.6.51, 8.7.40, 9.5.25, 10.4.14 (or the latest patched release for your respective branch) resolves the vulnerability.
Is typo3/cms affected?
Yes, typo3/cms is affected in releases prior to 11.1.1, 10.4.14, 9.5.25. Upgrade your dependency to 11.1.1, 10.4.14, 9.5.25 or later.
Is typo3/cms-backend affected?
Yes, typo3/cms-backend is affected in releases prior to 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1. Upgrade your dependency to 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1 or later.
What is the CVSS score of CVE-2021-21370?
CVE-2021-21370 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-2021-21370?
CVE-2021-21370 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-2021-21370?
Run the dependency tree command: 'inspect dependencies for typo3/cms'. 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-x7hc-x7fm-f7qh",
  "modified" : "2024-02-02T16:44:14Z",
  "published" : "2021-03-23T01:54:17Z",
  "aliases" : [ "CVE-2021-21370" ],
  "summary" : "Cross-Site Scripting in Content Preview (CType menu)",
  "details" : "### Problem\nIt has been discovered that content elements of type _menu_ are vulnerable to cross-site scripting when their referenced items get previewed in the page module. A valid backend user account is needed to exploit this vulnerability.\n\n### Solution\nUpdate to TYPO3 versions 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1 that fix the problem described.\n\n### Credits\nThanks to TYPO3 contributor Oliver Bartsch who reported and fixed the issue.\n\n### References\n* [TYPO3-CORE-SA-2021-008](https://typo3.org/security/advisory/typo3-core-sa-2021-008)",
  "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" : "typo3/cms-backend"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.0.0"
      }, {
        "fixed" : "7.6.51"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 7.6.50"
    }
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms-backend"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.7.40"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 8.7.39"
    }
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms-backend"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "9.0.0"
      }, {
        "fixed" : "9.5.25"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 9.5.24"
    }
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms-backend"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "10.0.0"
      }, {
        "fixed" : "10.4.14"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 10.4.13"
    }
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms-backend"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "11.0.0"
      }, {
        "fixed" : "11.1.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 11.1.0"
    }
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "10.0.0"
      }, {
        "fixed" : "10.4.14"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "11.0.0"
      }, {
        "fixed" : "11.1.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "9.0.0"
      }, {
        "fixed" : "9.5.25"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "10.0.0"
      }, {
        "fixed" : "10.4.14"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "11.0.0"
      }, {
        "fixed" : "11.1.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "9.0.0"
      }, {
        "fixed" : "9.5.25"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-x7hc-x7fm-f7qh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21370"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/typo3/cms-core/CVE-2021-21370.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/typo3/cms/CVE-2021-21370.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://packagist.org/packages/typo3/cms-backend"
  }, {
    "type" : "WEB",
    "url" : "https://typo3.org/security/advisory/typo3-core-sa-2021-008"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-03-23T01:42:20Z",
    "nvd_published_at" : "2021-03-23T02:15:00Z"
  }
}