CVE-2026-24778 is a cross-site scripting (XSS) vulnerability classified under CWE-79 affecting the TryGhost Ghost content management system (CMS) and its Portal component. The vulnerability exists in Ghost versions 5.43.0 through 5.120.4 and 6.0.0 through 6.14.0, and Portal versions 2.29.1 through 2.51.4 and 2.52.0 through 2.57.0. The root cause is improper neutralization of input during web page generation, allowing an attacker to craft a malicious URL that executes arbitrary JavaScript code in the context of an authenticated staff user or member who clicks the link. This script execution occurs with the victim’s permissions, potentially enabling account takeover, unauthorized content modification, or other malicious actions. The attack requires user interaction (clicking the malicious link) but no prior privileges or authentication by the attacker. Ghost CMS automatically loads the latest Portal component via CDN, so upgrading Ghost to versions 5.121.0 or later (which includes Portal 2.51.5) or 6.15.0 or later (which includes Portal 2.57.1) mitigates the vulnerability. For installations using customized or self-hosted Portal versions, manual updates or rebuilds are necessary to apply the patch. The vulnerability has a CVSS v3.1 score of 8.8 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), indicating a high-severity risk with network attack vector, low attack complexity, no privileges required, user interaction required, unchanged scope, and high impact on confidentiality, integrity, and availability. No known exploits have been reported in the wild as of the publication date.

For European organizations using the affected versions of Ghost CMS, this vulnerability poses a significant risk. Successful exploitation can lead to account takeover of staff or member accounts, which may allow attackers to modify or delete website content, inject malicious code, steal sensitive data, or escalate privileges. Given that Ghost is often used for publishing and content management, such compromise can damage organizational reputation, lead to data breaches, and disrupt business operations. The vulnerability’s exploitation requires user interaction but no prior authentication, increasing the attack surface especially in environments where staff or members frequently access links from external sources. Since Ghost automatically loads Portal components via CDN, organizations relying on default configurations can mitigate risk by upgrading Ghost itself. However, those with customized or self-hosted Portal versions must ensure manual patching to avoid persistent exposure. The high CVSS score reflects the potential for widespread impact on confidentiality, integrity, and availability of web assets. In regulated sectors within Europe, such as finance, healthcare, or government, exploitation could also lead to compliance violations and legal consequences.

1. Upgrade Ghost CMS to version 5.121.0 or later if using the 5.x branch, or to version 6.15.0 or later if using the 6.x branch, to automatically receive the patched Portal component via CDN. 2. For installations with customized or self-hosted Portal components, manually update or rebuild the Portal to versions 2.51.5 or later (for 5.x) and 2.57.1 or later (for 6.x) to apply the patch. 3. Implement strict Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of potential XSS attacks. 4. Educate staff and members about the risks of clicking on unsolicited or suspicious links, especially those received via email or messaging platforms. 5. Regularly audit and monitor web application logs for unusual activities or signs of XSS exploitation attempts. 6. Employ web application firewalls (WAFs) with updated rules to detect and block XSS payloads targeting Ghost CMS. 7. Conduct periodic security assessments and penetration testing focused on web application vulnerabilities to identify and remediate similar issues proactively.