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Member account takeover

Moderate
matthanley published GHSA-65p7-pjj8-ggmr Sep 23, 2021

Package

npm ghost (npm)

Affected versions

>=3.18.0 <=4.15.0

Patched versions

4.15.1, 3.42.6

Description

Impact

An error in the implementation of the member email change functionality allows unauthenticated users to change the email address of arbitrary member accounts to one they control by crafting a request to the relevant API endpoint, and validating the new address via magic link sent to the new email address.

Ghost(Pro) has already been patched. Self-hosters are impacted if running Ghost a version between 3.18.0 and 4.15.0 with members functionality enabled.

Patches

Fixed in 4.15.1, all 4.x sites should upgrade as soon as possible.
Fixed in 3.42.6, all 3.x sites should upgrade as soon as possible.

Workarounds

The patch in 4.15.1 and 3.42.6 adds a new authenticated endpoint for updating member email addresses. Updating Ghost is the quickest complete solution.

As a workaround, if for any reason you cannot update your Ghost instance, you can block the POST /members/api/send-magic-link/ endpoint, which will also disable member login and signup for your site.

For more information

If you have any questions or comments about this advisory:

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVE ID

No known CVE

Weaknesses

No CWEs

Credits