GHSA-2VCC-5V34-9JC8

Vulnerability from github – Published: 2026-06-18 13:07 – Updated: 2026-06-18 13:07
VLAI
Summary
TinaCMS rich-text (slatejson) rendering does not sanitize link/image URLs, allowing stored XSS via dangerous URL schemes
Details

TinaCMS rich-text parsing and the default link/image renderers did not sanitize the url field on Slate link/image nodes. Content containing javascript: or data:text/html URLs — including case-variant, whitespace-padded, and control-character-obfuscated forms — is rendered into href/src and executes when the content is viewed. Any actor able to author rich-text content (for example a lower-privileged editor, or imported/external content) can achieve stored XSS against editors and site viewers.

Fixed in https://github.com/tinacms/tinacms/pull/7056 via a sanitizeUrl() helper (case-insensitive, whitespace/control-character-normalized scheme allow-list) applied recursively to Slate trees at parse time and in the default rich-text rendering.

Severity
4.8 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "tinacms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.9.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "@tinacms/mdx"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55661"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79",
      "CWE-87"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-18T13:07:05Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "TinaCMS rich-text parsing and the default link/image renderers did not sanitize the `url` field on Slate link/image nodes. Content containing `javascript:` or `data:text/html` URLs \u2014 including case-variant, whitespace-padded, and control-character-obfuscated forms \u2014 is rendered into `href`/`src` and executes when the content is viewed. Any actor able to author rich-text content (for example a lower-privileged editor, or imported/external content) can achieve stored XSS against editors and site viewers.\n\nFixed in https://github.com/tinacms/tinacms/pull/7056 via a `sanitizeUrl()` helper (case-insensitive, whitespace/control-character-normalized scheme allow-list) applied recursively to Slate trees at parse time and in the default rich-text rendering.",
  "id": "GHSA-2vcc-5v34-9jc8",
  "modified": "2026-06-18T13:07:05Z",
  "published": "2026-06-18T13:07:05Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/tinacms/tinacms/security/advisories/GHSA-2vcc-5v34-9jc8"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tinacms/tinacms/pull/7056"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/tinacms/tinacms"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "TinaCMS rich-text (slatejson) rendering does not sanitize link/image URLs, allowing stored XSS via dangerous URL schemes"
}


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