CVE-2026-53943: Ghost Cross-Site Scripting Vulnerability

CRITICAL
Advisory Identifier: GHSA-62q6-4hv4-vjrw
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CVSS 9.6
CWE-524
Published
Advisory Summary

CVE-2026-53943 is a CRITICAL (CVSS 9.6) cross-site scripting vulnerability (CWE-524: Use of Cache Containing Sensitive Information) affecting Ghost libraries in the npm ecosystem. The issue involves cache-poisoning xss in ghost frontend via x-ghost-preview header. Remediation is available by upgrading affected packages to version 6.37.0.

CVE-2026-53943 at a Glance

CVE Identifier CVE-2026-53943
GHSA Identifier GHSA-62q6-4hv4-vjrw
Severity CRITICAL
CVSS v3.1 Base Score 9.6
CWE Classification CWE-524: Use of Cache Containing Sensitive Information
Affected Product Ghost
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 9.6

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

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

How to Fix CVE-2026-53943

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

ghost fixed: 6.37.0 
npm install ghost@6.37.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls ghost

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-53943, inspect your project dependencies using npm:

npm ls ghost

Analyze the terminal output to locate any version of Ghost in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.37.0), your application is affected.

Note: The npm ls ghost command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-524: Use of Cache Containing Sensitive Information, where the code uses a cache that contains sensitive information, but the cache can be read by an actor outside of the intended control sphere. In Ghost, 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

### Impact When Ghost is behind a shared caching layer that results in cached content being shared between different visitors (e.g., Fastly, Cloudflare, nginx proxy_cache, and others), an unauthenticated user could send an `x-ghost-preview` header that altered the rendered frontend response. In affected cache configurations, that response could be stored and served to subsequent visitors requesting the same page, allowing cache poisoning of request-specific preview output. When running Ghost's frontend and admin panel on the same domain this could be used to take over staff user accounts. When running these on different domains staff accounts have no exposure. ### Vulnerable versions This vulnerability is present in Ghost from v4.0 up to v6.36.0. ### Patches v6.37.0 contains a fix for this issue. ### How to update For self-hosters using Docker, find [Docker's official Ghost image here](https://hub.docker.com/_/ghost). Updating a Docker-based Ghost instance [is documented here](https://docs.ghost.org/install/docker#updating-ghost). If your Ghost is a Ghost-CLI install see our documentation on [updating it to the latest version here](https://docs.ghost.org/update). If you suspect a credential compromise, use the “Reset all authentication” dialogue under Settings / Danger Zone. This is available starting with Ghost v6.41.0. ### Workarounds At the caching layer, bypass the cache for `x-ghost-preview` requests. ### References Ghost thanks [CryptoCat](https://linkedin.com/in/cryptocat) for disclosing this vulnerability responsibly. ### For more information If you have any questions or comments about this advisory, email us at [security@ghost.org](mailto:security@ghost.org).

CVE-2026-53943 Affected Ghost Versions

1 component(s)
Fixed Versions:
6.37.0
Product / Package Ecosystem Affected Versions Fixed Version
ghost
npm/ghost
npm
≥ 4.0.0
< 6.37.0
6.37.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/TryGhost/Ghost/security/advisories/GHSA-62q6-4hv4-vjrw
NVD — CVE-2026-53943 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-53943
Ghost Source Repository REPOSITORY
https://github.com/TryGhost/Ghost

Frequently Asked Questions

What is CVE-2026-53943?
CVE-2026-53943 is a security vulnerability in Ghost involving Cache-poisoning XSS in Ghost frontend via x-ghost-preview header under CWE-524: Use of Cache Containing Sensitive Information.
Which Ghost versions are affected?
Affected versions include releases prior to 6.37.0 across affected packages: ghost.
What version fixes CVE-2026-53943?
Upgrading to 6.37.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is ghost affected?
Yes, ghost is affected in releases prior to 6.37.0. Upgrade your dependency to 6.37.0 or later.
What is the CVSS score of CVE-2026-53943?
CVE-2026-53943 has a CVSS v3.1 base score of 9.6 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.
What CWE is associated with CVE-2026-53943?
CVE-2026-53943 is classified under CWE-524: Use of Cache Containing Sensitive Information (The code uses a cache that contains sensitive information, but the cache can be read by an actor outside of the intended control sphere.).
How can I check npm dependencies for CVE-2026-53943?
Run the dependency tree command: 'npm ls ghost'. 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-62q6-4hv4-vjrw",
  "modified" : "2026-07-01T21:58:32Z",
  "published" : "2026-07-01T21:58:32Z",
  "aliases" : [ "CVE-2026-53943" ],
  "summary" : "Ghost: Cache-poisoning XSS in Ghost frontend via x-ghost-preview header",
  "details" : "### Impact\n\nWhen Ghost is behind a shared caching layer that results in cached content being shared between different visitors (e.g., Fastly, Cloudflare, nginx proxy_cache, and others), an unauthenticated user could send an `x-ghost-preview` header that altered the rendered frontend response. In affected cache configurations, that response could be stored and served to subsequent visitors requesting the same page, allowing cache poisoning of request-specific preview output. \n\nWhen running Ghost's frontend and admin panel on the same domain this could be used to take over staff user accounts. When running these on different domains staff accounts have no exposure. \n\n### Vulnerable versions\n\nThis vulnerability is present in Ghost from v4.0 up to v6.36.0.\n\n### Patches\n\nv6.37.0 contains a fix for this issue.\n\n### How to update\n\nFor self-hosters using Docker, find [Docker's official Ghost image here](https://hub.docker.com/_/ghost). Updating a Docker-based Ghost instance [is documented here](https://docs.ghost.org/install/docker#updating-ghost).\n\nIf your Ghost is a Ghost-CLI install see our documentation on [updating it to the latest version here](https://docs.ghost.org/update).\n\nIf you suspect a credential compromise, use the “Reset all authentication” dialogue under Settings / Danger Zone. This is available starting with Ghost v6.41.0. \n\n### Workarounds\n\nAt the caching layer, bypass the cache for `x-ghost-preview` requests. \n\n### References\n\nGhost thanks [CryptoCat](https://linkedin.com/in/cryptocat) for disclosing this vulnerability responsibly.\n\n### For more information\n\nIf you have any questions or comments about this advisory, email us at [security@ghost.org](mailto:security@ghost.org).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "ghost"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "fixed" : "6.37.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 6.36.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/TryGhost/Ghost/security/advisories/GHSA-62q6-4hv4-vjrw"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-53943"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/TryGhost/Ghost"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-524" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-01T21:58:32Z",
    "nvd_published_at" : "2026-06-24T19:17:11Z"
  }
}