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Fencer Intel
medium 6.8

CVE-2021-29484 json

DOM XSS in Theme Preview

published 5y ago modified 2mo ago also BIT-ghost-2021-29484 , EUVD-2021-0804 , GHSA-9fgx-q25h-jxrg

cvss
6.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
7.9%
EPSS 7.9% chance of exploitation in 30 days, percentile 94%
public exploits
0
none known, plus a Nuclei check

Summary

Ghost is a Node.js CMS. 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. The issue has been 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. As a workaround blocking access to /ghost/preview can also mitigate the issue.

Patch / fix

  • npm ghost 4.3.3
  • bitnami ghost 4.3.3
  • ghost ghost 4.3.3

Is CVE-2021-29484 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

7.94% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • Nuclei template Ghost CMS <=4.32 - Cross-Site Scripting nuclei detection template
  • blog.sonarsource.com https://blog.sonarsource.com/ghost-admin-takeover referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
GitHub 3.1 6.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
CNA 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N
OSV 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm ghost
>=4.0.0, <4.3.3
4.3.3
bitnami ghost
>=4.0.0, <4.3.3
4.3.3

Affected products

  • TryGhost Ghost

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.