ActivityPub Server Vulnerability in Ghost by TryGhost
CVE-2026-63115

5.3MEDIUM

Key Information:

Vendor

Tryghost

Status
Activitypub
Vendor
CVE Published:
30 October 2026

What is CVE-2026-63115?

The ActivityPub server for Ghost, developed with Fedify, has a remote activity manipulation vulnerability. This allows unauthenticated federated servers to impersonate other accounts during follow or repost actions. Although no private information is leaked and existing relationships can be restored, the flaw raises significant risks for account management and integrity. Users should update to version 1.2.6 to safeguard against this issue. Self-hosted installations require updated images and redeployment to mitigate the risk.

Affected Version(s)

ActivityPub >= 1.0.0, < 1.2.6

References

https://github.com/TryGhost/ActivityPub/security/advisori...
x_refsource_CONFIRM
https://github.com/TryGhost/ActivityPub/pull/1929
x_refsource_MISC
https://github.com/TryGhost/ActivityPub/commit/1526f540b9...
x_refsource_MISC

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.