GHSA-xpp7-93x6-v29m: 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.
Details
Original advisory: https://github.com/advisories/GHSA-xpp7-93x6-v29m
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-539500.20% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 11% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-53950 | coverage & exploitation status | NVD · CVE.org |
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