CVE-2026-53944 is a medium-severity (CVSS 5.8) CWE-184 vulnerability in ghost. A fix is available for ghost — see the affected versions and patch details below.
Ghost: Private IP filtering bypass to make server-side requests to internal services
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-53944.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
ghostnpmDescription
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 [email protected].
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | ghost | ≥ 6.0.9&&< 6.21.1 | 6.21.1npm install ghost@6.21.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ghost, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ghost to 6.21.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-53944 is resolved across your whole dependency graph.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.
Frequently Asked Questions
Is CVE-2026-53944 in your dependencies?
Find it across npm, including transitive dependencies.