ghsa-hr3h-x6gq-rqcp
Vulnerability from github
Published
2021-08-25 14:45
Modified
2025-04-17 12:45
Severity ?
5.9 (Medium) - CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L
Summary
Cross site scripting via HTML attributes in the back end
Details

Impact

It is possible for untrusted users to inject malicious code into HTML attributes in the back end, which will be executed both in the element preview (back end) and on the website (front end).

Installations are only affected if there are untrusted back end users who have the rights to modify HTML fields (e.g. TinyMCE).

Patches

Update to Contao 4.4.56, 4.9.18 or 4.11.7

Workarounds

Disable all fields that allow HTML for untrusted back end users or disable the login for these users.

References

https://contao.org/en/security-advisories/cross-site-scripting-via-html-attributes-in-the-back-end

For more information

If you have any questions or comments about this advisory, open an issue in contao/contao.

Credits

Thanks to Mikhail Khramenkov and Moritz Vondano for reporting this security issue.

Show details on source website

To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "contao/core-bundle"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.4.56"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "contao/contao"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.4.56"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "contao/contao"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.5.0"
            },
            {
              "fixed": "4.9.18"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "contao/contao"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.10.0"
            },
            {
              "fixed": "4.11.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "contao/core-bundle"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.5.0"
            },
            {
              "fixed": "4.9.18"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "contao/core-bundle"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.10.0"
            },
            {
              "fixed": "4.11.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-35955"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-08-24T18:55:48Z",
    "nvd_published_at": "2021-08-12T15:15:00Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nIt is possible for untrusted users to inject malicious code into HTML attributes in the back end, which will be executed both in the element preview (back end) and on the website (front end).\n\nInstallations are only affected if there are untrusted back end users who have the rights to modify HTML fields (e.g. TinyMCE).\n\n### Patches\n\nUpdate to Contao 4.4.56, 4.9.18 or 4.11.7\n\n### Workarounds\n\nDisable all fields that allow HTML for untrusted back end users or disable the login for these users.\n\n### References\n\nhttps://contao.org/en/security-advisories/cross-site-scripting-via-html-attributes-in-the-back-end\n\n### For more information\n\nIf you have any questions or comments about this advisory, open an issue in [contao/contao](https://github.com/contao/contao/issues/new/choose).\n\n### Credits\n\nThanks to Mikhail Khramenkov and Moritz Vondano for reporting this security issue.",
  "id": "GHSA-hr3h-x6gq-rqcp",
  "modified": "2025-04-17T12:45:11Z",
  "published": "2021-08-25T14:45:01Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/contao/contao/security/advisories/GHSA-hr3h-x6gq-rqcp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-35955"
    },
    {
      "type": "WEB",
      "url": "https://contao.org/en/news/contao-4-9-16-and-4-11-5-are-available.html"
    },
    {
      "type": "WEB",
      "url": "https://contao.org/en/security-advisories/cross-site-scripting-via-html-attributes-in-the-back-end.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/contao/CVE-2021-35955.yaml"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/core-bundle/CVE-2021-35955.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/contao/contao"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Cross site scripting via HTML attributes in the back end"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.