4.3 Medium
CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:M/Au:N/C:N/I:P/A:N
6.8 Medium
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
0.015 Low
EPSS
Percentile
86.9%
An unused endpoint added during the development of 4.0.0 has left sites vulnerable to untrusted users gaining access to Ghost Admin. Attackers can gain access by getting logged in users to click a link containing malicious code. Users do not need to enter credentials and may not know they’ve visited a malicious site.
Ghost(Pro) has already been patched. We can find no evidence that the issue was exploited on Ghost(Pro) prior to the patch being added.
Self-hosters are impacted if running Ghost a version between 4.0.0 and 4.3.2. Immediate action should be taken to secure your site - see patches & workarounds below.
Fixed in 4.3.3, all 4.x sites should upgrade as soon as possible.
As the endpoint is unused, the patch simply removes it.
/ghost/preview
Example of how to block access in nginx:
location ~ /ghost/preview {
rewrite ^(\/(.*\/)?ghost\/)(.*)$ $1 redirect;
}
This redirects the endpoint to /ghost/
, which mimics the behaviour after the patch is applied.
If you have any questions or comments about this advisory:
Credits: Paul Gerste, SonarSource (https://www.sonarsource.com/)
blog.sonarsource.com/ghost-admin-takeover
forum.ghost.org/t/critical-security-update-available-for-ghost-4-x/22290
github.com/advisories/GHSA-9fgx-q25h-jxrg
github.com/TryGhost/Ghost/commit/14b3431de12e674a0bd562e9230e2891b6903ae2
github.com/TryGhost/Ghost/security/advisories/GHSA-9fgx-q25h-jxrg
nvd.nist.gov/vuln/detail/CVE-2021-29484
security.netapp.com/advisory/ntap-20210618-0006/
www.npmjs.com/package/ghost
4.3 Medium
CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:M/Au:N/C:N/I:P/A:N
6.8 Medium
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
0.015 Low
EPSS
Percentile
86.9%