Impact
A vulnerability in Ghost's public donation checkout flow allowed an unauthenticated attacker to obtain full paid gift memberships for a minimal payment. No customer or member data was exposed, and the issue could not be used to steal money from a site or its members.
Vulnerable versions
This vulnerability is present in Ghost from v6.27.0 up to v6.43.1.
Patches
v6.44.0 contains a fix for this issue.
How to update
For self-hosters using Docker, find Docker’s official Ghost image on Docker Hub and follow the documentation on updating a Docker-based Ghost instance.
For self-hosters using Ghost-CLI, see the documentation for updating Ghost to the latest version.
Workarounds
If upgrading immediately is not possible, you can remove the vulnerable checkout path by disabling the donations feature in Ghost Admin under Settings → Membership → Tips & donations until the upgrade is applied.
References
Ghost thanks sane100400 and p4p3r for disclosing this vulnerability responsibly.
For more information
If you have any questions or comments about this advisory, email Ghost at security@ghost.org.
Impact
When making an external request, it is possible to bypass the IP filter that ensures the request isn't going to an internal service using an IPv6 literal which maps to a private IPv4 address.
Vulnerable versions
This vulnerability is present in Ghost from v6.0.9 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. Updating a Docker-based Ghost instance is documented here.
If your Ghost is a Ghost-CLI install see our documentation on updating it to the latest version here.
References
Ghost thanks l3tchupkt for disclosing this vulnerability responsibly.
For more information
If you have any questions or comments about this advisory, email us at security@ghost.org.
Impact
Ghost’s private-IP check for outbound HTTP requests could be bypassed via DNS rebinding, allowing an attacker to coerce the Ghost server into reaching hosts on internal networks through features that issue external fetches.
Vulnerable versions
This vulnerability is present in Ghost from v6.0.9 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. Updating a Docker-based Ghost instance is documented here.
If your Ghost is a Ghost-CLI install see our documentation on updating it to the latest version here.
Workarounds
If upgrading immediately is not possible, operators can reduce exposure by preventing the Ghost server from reaching sensitive internal ranges at the network layer — for example, egress firewall rules that block the Ghost process from initiating connections to RFC1918 networks, loopback, link-local (including 169.254.169.254) and any other internal service ranges. Disabling features that trigger outbound fetches (oEmbed, webmentions, recommendations) will further limit the attack surface but does not remove the underlying issue.
References
Ghost thanks Oluwaseun Esther Folorunsho, Lakshmikanthan K (@l3tchupkt), Offgrid Security, and Baki for disclosing this vulnerability responsibly.
For more information
If you have any questions or comments about this advisory, email us at security@ghost.org.
Impact An attacker was able to craft a malicious link that, when accessed by an authenticated staff user or member, would execute JavaScript with the victim's permissions, potentially leading to account takeover.
Vulnerable versions This vulnerability is present in Ghost versions: - v5.43.0 to v5.120.4 - v6.0.0 to v6.14.0
As well as in Portal versions: - v2.29.1 to v2.51.4 - v2.52.0 to v2.57.0
Patches Ghost automatically loads the latest patch of the members Portal component via CDN. Therefore: - For Ghost 5.x users, upgrading to v5.121.0 or later fixes the vulnerability (loads Portal v2.51.5, which contains the patch) - For Ghost 6.x users, upgrading to v6.15.0 or later fixes the vulnerability (loads Portal v2.57.1, which contains the patch)
For Ghost installations using a customised or self-hosted version of Portal, it will be necessary to manually rebuild from or update to the latest patch version.
References Ghost thanks Younes Belalia for discovering and disclosing this vulnerability responsibly.
For more information If users have any questions or comments about this advisory, email Ghost at security@ghost.org.