CVE-2026-53943 Ghost: Cache-poisoning XSS in Ghost frontend via x-ghost-preview header
Unauthenticated attackers can poison shared caches via the x-ghost-preview header to inject XSS, potentially taking over staff accounts if frontend and admin share a domain.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-53943?
CVE-2026-53943 is a critical cross-site scripting vulnerability in TryGhost Ghost, published on 24 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Ghost is a Node.js content management system. From until 6.37.0, when Ghost is behind a shared caching layer that results in cached content being shared between different visitors, an unauthenticated user could send an x-ghost-preview header that altered the rendered frontend response. In affected cache configurations, that response could be stored and served to subsequent visitors requesting the same page, allowing cache poisoning of request-specific preview output. When running Ghost's frontend and admin panel on the same domain this could be used to take over staff user accounts. When running these on different domains staff accounts have no exposure. This vulnerability is fixed in 6.37.0.
Weakness: CWE-524
Which versions are affected by CVE-2026-53943?
3 open source packages ship an affected version, including ghost.
| Package | Affected | Fixed in |
|---|---|---|
ghost Bitnami | From 4.0.0 | 6.37.0 |
ghost npm | From 4.0.0 | 6.37.0 |
ghost npm | From 4.0.0 | 6.37.0 |
How do I fix CVE-2026-53943?
Upgrade ghost to 6.37.0 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-53943 being exploited?
There is no known exploitation of CVE-2026-53943 in the wild and no public exploit code.
Sources
Also known as BIT-ghost-2026-53943, GHSA-62q6-4hv4-vjrw.