XSS in Ghost's ActivityPub client
Impact
The ActivityPub client in Ghost was vulnerable to JavaScript injection on posts shared by a maliciously customised ActivityPub server.
Vulnerable Versions
This vulnerability is present in the @tryghost/activitypub package up to v3.0.8. All prior versions are also affected.
Patches
@tryghost/activitypub v3.1.0 contains a fix for this issue and is also automatically fetched by Ghost.
References
Ghost thanks Brad Geesaman, Ghost Security for disclosing this vulnerability responsibly.
For more information
If you have any questions or comments about this advisory, email Ghost at security@ghost.org.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @tryghost/activitypub | < 3.1.0 | 3.1.0 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-79- Platform
- npm
- Package
@tryghost/activitypub- Disclosed
- 04.08.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-xpp7-93x6-v29m - CC BY 4.0
Vulnerability history: @tryghost/activitypub
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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