CVE-2026-55103
HIGH
MEDIUM
Priority: 0.02
BB Relevance:
77/100
Published: 2026-10-15
Modified: 2026-10-28
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
No Auth
No Interaction
Conf. Impact
Scope Change
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
None
S:
Changed
C:
High
I:
None
A:
None
Description
Discourse ActivityPub adds ActivityPub support to Discourse. Prior to commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5, inbound ActivityPub processing does not sufficiently verify that the actor authenticated by the signed request matches the Activity actor and owns the referenced federated post. A remote attacker can exploit these missing identity and ownership checks to edit, delete, or reply to federated posts without the required permissions. This vulnerability is fixed with commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5.
Affected Software (1)
| Vendor | Product | Version |
|---|---|---|
| discourse | discourse-activity-pub | < 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5 |