CVE-2026-63115
MEDIUM
MEDIUM
Priority: 0.01
BB Relevance:
71/100
Published: 2026-10-30
Modified: 2026-11-02
First seen: 2026-10-30
Status: active
Attack Surface
Network
Low Complexity
No Auth
No Interaction
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
None
S:
Unchanged
C:
None
I:
Low
A:
None
Description
ActivityPub is a multi-tenant ActivityPub server for Ghost, built with Fedify. From 1.0.0 until 1.2.6, the `Undo` handler allows a remote federated server to cause the service to act on a `follow` or `repost` as though the activity came from a different account. This permits removal of an existing `follow` relationship or `repost` belonging to another account without that account's involvement. No private data is exposed and content is not modified; the affected relationships can be re-established. Services proxying to Ghost's hosted ActivityPub server have already been updated, while self-hosted services require an updated image and redeployment. This issue is fixed in version 1.2.6.
Weakness Classification (3)
Affected Software (2)
| Vendor | Product | Version |
|---|---|---|
| TryGhost | ActivityPub | >= 1.0.0, < 1.2.6 |
| TryGhost | ActivityPub | >= 1.0.0, < 1.2.6 |
References & Advisories (4)
x_refsource_MISC
x_refsource_MISC
x_refsource_MISC
x_refsource_CONFIRM