Vulnerability-Lookup

CVE-2026-55660 (GCVE-0-2026-55660)

Vulnerability from cvelistv5 – Published: 2026-07-01 21:00 – Updated: 2026-07-02 12:43

Title

TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover

Summary

Tina is a headless content management system. In versions prior to @tinacms/app 2.5.6 and tinacms 3.9.3, cross-origin postMessage handlers and a rich-text URL-sanitization bypass enable stored XSS and session takeover. The library registers window message listeners — the useTina overlay handler, the OAuth authentication popup handler, and the admin↔preview iframe GraphQL reducer — that act on event.data without verifying event.origin or event.source and post messages using non-specific target origins, while insufficient URL sanitization in rich-text content allows malicious URLs to persist and execute. A page the victim visits (or a window in an opener/iframe relationship with a Tina admin) can forge messages to drive the editor, inject preview content, or observe/forge the OAuth popup channel to take over an authenticated editing session. This issue has been fixed in versions @tinacms/app 2.5.6 and tinacms 3.9.3.

Severity

7.6 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator (v2.0.3)

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-346 - Origin Validation Error
CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')
CWE-940 - Improper Verification of Source of a Communication Channel

Assigner

GitHub_M

References

2 references

URL	Tags
https://github.com/tinacms/tinacms/security/advis…	x_refsource_CONFIRM
https://github.com/tinacms/tinacms/pull/7056	x_refsource_MISC

Impacted products

2 products

Vendor	Product	Version
tinacms	tinacms	Affected: < 3.9.3
tinacms	@tinacms/app	Affected: < 2.5.6

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-55660

Vulnerability from fkie_nvd - Published: 2026-07-01 21:17 - Updated: 2026-07-02 17:45

Severity

7.6 (High) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/tinacms/tinacms/pull/7056
	security-advisories@github.com	https://github.com/tinacms/tinacms/security/advisories/GHSA-g5qx-h5f3-mp2f

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "tinacms",
          "vendor": "tinacms",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.9.3"
            }
          ]
        },
        {
          "product": "@tinacms/app",
          "vendor": "tinacms",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.5.6"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Tina is a headless content management system. In versions prior to @tinacms/app 2.5.6 and tinacms 3.9.3, cross-origin postMessage handlers and a rich-text URL-sanitization bypass enable stored XSS and session takeover. The library registers window message listeners \u2014 the useTina overlay handler, the OAuth authentication popup handler, and the admin\u2194preview iframe GraphQL reducer \u2014 that act on event.data without verifying event.origin or event.source and post messages using non-specific target origins, while insufficient URL sanitization in rich-text content allows malicious URLs to persist and execute. A page the victim visits (or a window in an opener/iframe relationship with a Tina admin) can forge messages to drive the editor, inject preview content, or observe/forge the OAuth popup channel to take over an authenticated editing session. This issue has been fixed in versions @tinacms/app 2.5.6 and tinacms 3.9.3."
    }
  ],
  "id": "CVE-2026-55660",
  "lastModified": "2026-07-02T17:45:00.780",
  "metrics": {
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      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
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          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 7.6,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
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}

GHSA-G5QX-H5F3-MP2F

Vulnerability from github – Published: 2026-06-19 21:15 – Updated: 2026-06-19 21:15

Summary

TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover

Details

TinaCMS registers window message listeners — the useTina overlay handler, the OAuth authentication popup handler, and the admin↔preview iframe GraphQL reducer — that act on event.data without verifying event.origin or event.source, and post messages using non-specific target origins. A page the victim visits (or a window in an opener/iframe relationship with a Tina admin) can forge messages to drive the editor, inject preview content, or observe/forge the OAuth popup channel to take over an authenticated editing session.

Fixed in #7056 by allow-listing trusted origins and verifying event.source (isFromAdmin, isFromTrustedPreviewOrigin), and by posting only to explicit target origins (never "*").

Note: the rich-text URL-sanitization issue previously bundled here has been split into its own advisory (GHSA-2vcc-5v34-9jc8) so each vulnerability can receive a distinct CVE.

Severity

8.5 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
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        "ecosystem": "npm",
        "name": "tinacms"
      },
      "ranges": [
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          "events": [
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              "introduced": "0"
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            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
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        "ecosystem": "npm",
        "name": "@tinacms/app"
      },
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          "events": [
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            {
              "fixed": "2.5.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55660"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346",
      "CWE-601",
      "CWE-79",
      "CWE-940"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-19T21:15:29Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "TinaCMS registers window message listeners \u2014 the useTina overlay handler, the OAuth authentication popup handler, and the admin\u2194preview iframe GraphQL reducer \u2014 that act on event.data without verifying event.origin or event.source, and post messages using non-specific target origins. A page the victim visits (or a window in an opener/iframe relationship with a Tina admin) can forge messages to drive the editor, inject preview content, or observe/forge the OAuth popup channel to take over an authenticated editing session.\n\nFixed in [#7056](https://github.com/tinacms/tinacms/pull/7056) by allow-listing trusted origins and verifying event.source (isFromAdmin, isFromTrustedPreviewOrigin), and by posting only to explicit target origins (never \"*\").\n\nNote: the rich-text URL-sanitization issue previously bundled here has been split into its own advisory (GHSA-2vcc-5v34-9jc8) so each vulnerability can receive a distinct CVE.",
  "id": "GHSA-g5qx-h5f3-mp2f",
  "modified": "2026-06-19T21:15:29Z",
  "published": "2026-06-19T21:15:29Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/tinacms/tinacms/security/advisories/GHSA-g5qx-h5f3-mp2f"
    },
    {
      "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:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-55660 (GCVE-0-2026-55660)

FKIE_CVE-2026-55660

GHSA-G5QX-H5F3-MP2F

Tags

Sightings

Nomenclature