CVE-2026-53946: Ghost Mobiledoc Image-size Fetch SSRF Vulnerability

MODERATE
Advisory Identifier: GHSA-g366-23fw-ggp6
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CVSS 5.4
CWE-918
Published
Advisory Summary

CVE-2026-53946 is a MODERATE (CVSS 5.4) mobiledoc image-size fetch ssrf vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Ghost libraries in the npm ecosystem. The issue involves mobiledoc image-size fetch ssrf. Remediation is available by upgrading affected packages to version 6.21.2.

CVE-2026-53946 at a Glance

CVE Identifier CVE-2026-53946
GHSA Identifier GHSA-g366-23fw-ggp6
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-918: Server-Side Request Forgery (SSRF)
Affected Product Ghost
Package Ecosystem npm
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-2026-53946

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: 6.21.2 
npm install ghost@6.21.2
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-2026-53946, 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 6.21.2), 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-918: Server-Side Request Forgery (SSRF), where the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination. 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 re-rendering posts, Ghost would refetch missing image dimensions by issuing an outbound HTTP request to the URL stored on an image card — without restricting that URL to trusted image hosts. An authenticated staff user able to create or edit posts could therefore point an image card at an attacker-chosen host and cause the Ghost server to request it on their behalf, including hosts on internal networks or cloud instance metadata endpoints that would not normally be reachable from the public internet. ### Vulnerable versions This vulnerability is present in Ghost from v6.19.3 up to v6.21.0. ### Patches v6.21.1 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). ### For more information If you have any questions or comments about this advisory, email us at [security@ghost.org](mailto:security@ghost.org).

CVE-2026-53946 Affected Ghost Versions

1 component(s)
Fixed Versions:
6.21.2
Product / Package Ecosystem Affected Versions Fixed Version
ghost
npm/ghost
npm
≥ 6.19.4
< 6.21.2
6.21.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/TryGhost/Ghost/security/advisories/GHSA-g366-23fw-ggp6
NVD — CVE-2026-53946 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-53946
Ghost Source Repository REPOSITORY
https://github.com/TryGhost/Ghost/pull/26753
Security Fix Commit FIX COMMIT
https://github.com/TryGhost/Ghost/commit/ba692df7f27162d0440d57487f16c530416a8eb2
Ghost Source Repository REPOSITORY
https://github.com/TryGhost/Ghost
Ghost Release RELEASE
https://github.com/TryGhost/Ghost/releases/tag/v6.21.1

Frequently Asked Questions

What is CVE-2026-53946?
CVE-2026-53946 is a security vulnerability in Ghost involving Mobiledoc image-size fetch SSRF under CWE-918: Server-Side Request Forgery (SSRF).
Which Ghost versions are affected?
Affected versions include releases prior to 6.21.2 across affected packages: ghost.
What version fixes CVE-2026-53946?
Upgrading to 6.21.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is ghost affected?
Yes, ghost is affected in releases prior to 6.21.2. Upgrade your dependency to 6.21.2 or later.
What is the CVSS score of CVE-2026-53946?
CVE-2026-53946 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-2026-53946?
CVE-2026-53946 is classified under CWE-918: Server-Side Request Forgery (SSRF) (The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.).
How can I check npm dependencies for CVE-2026-53946?
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-g366-23fw-ggp6",
  "modified" : "2026-08-04T21:25:21Z",
  "published" : "2026-08-04T21:25:21Z",
  "aliases" : [ "CVE-2026-53946" ],
  "summary" : "Ghost: Mobiledoc image-size fetch SSRF",
  "details" : "### Impact\n\nWhen re-rendering posts, Ghost would refetch missing image dimensions by issuing an outbound HTTP request to the URL stored on an image card — without restricting that URL to trusted image hosts. An authenticated staff user able to create or edit posts could therefore point an image card at an attacker-chosen host and cause the Ghost server to request it on their behalf, including hosts on internal networks or cloud instance metadata endpoints that would not normally be reachable from the public internet.\n\n### Vulnerable versions\n\nThis vulnerability is present in Ghost from v6.19.3 up to v6.21.0.\n\n### Patches\n\nv6.21.1 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\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:L/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "ghost"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "6.19.4"
      }, {
        "fixed" : "6.21.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "< 6.21.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/TryGhost/Ghost/security/advisories/GHSA-g366-23fw-ggp6"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-53946"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/TryGhost/Ghost/pull/26753"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/TryGhost/Ghost/commit/ba692df7f27162d0440d57487f16c530416a8eb2"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/TryGhost/Ghost"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/TryGhost/Ghost/releases/tag/v6.21.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-04T21:25:21Z",
    "nvd_published_at" : "2026-06-24T19:17:12Z"
  }
}