CVE-2026-53950
Deferred Deferred - Pending Action

JavaScript Injection in Ghost ActivityPub Client

Publication date: 2026-06-24

Last updated on: 2026-06-24

Assigner: GitHub, Inc.

Description
@tryghost/activitypub is Ghost’s social/federation client app. Prior to 3.1.0, the ActivityPub client in Ghost was vulnerable to JavaScript injection on posts shared by a maliciously customised ActivityPub server. This vulnerability is fixed in 3.1.0.

CVSS Scores

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Meta Information

Published
2026-06-24
Last Modified
2026-06-24
Generated
2026-07-15
AI Q&A
2026-06-24
EPSS Evaluated
2026-07-13
NVD
CVE-2026-53950
EUVD
EUVD-2026-39019

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
ghost activitypub 3.1.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Attack-Flow Graph

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Compliance Impact

The vulnerability involves a Cross-Site Scripting (XSS) issue that allows JavaScript injection, leading to high risks to confidentiality, integrity, and availability of data.

Such risks could potentially impact compliance with standards and regulations like GDPR and HIPAA, which require protection of sensitive data and maintaining system integrity and availability.

However, the provided information does not explicitly state the direct effects on compliance with these regulations.

Impact Analysis

This vulnerability can have severe impacts including the execution of malicious JavaScript code in the context of the user's browser. This can lead to compromise of confidentiality, integrity, and availability of the affected system or data, as indicated by the CVSS score which rates the impact on confidentiality, integrity, and availability as high.

Executive Summary

The vulnerability exists in the ActivityPub client of Ghost, specifically in versions prior to 3.1.0. It allows JavaScript injection on posts that are shared by a maliciously customized ActivityPub server. This means that an attacker controlling such a server could inject harmful JavaScript code into posts viewed by users of the vulnerable Ghost client.

Mitigation Strategies

To mitigate this vulnerability, you should upgrade the @tryghost/activitypub client to version 3.1.0 or later, where the JavaScript injection issue has been fixed.

Detection Guidance

There is no specific information provided about detection methods or commands to identify the CVE-2026-53950 vulnerability on your network or system.

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