NodeBB does not bind the claimed author of an inbound ActivityPub object to the authenticated remote actor. The inbound middleware verifies the HTTP-signature actor and checks the origin of object.id, but never validates that attributedTo corresponds to the sender. In the object mock, attributedTo is used directly as a uid, and actors.assert silently ignores numeric identifiers (filtering them out without re-deriving the uid), so a federated remote actor can set attributedTo to a bare numeric value such as 1 and have the resulting post or private message created with that local uid as author, including the administrator account. This lets a remote attacker forge posts and direct messages attributed to arbitrary local users. Requires the ActivityPub/federation feature to be enabled.
References
| Link | Resource |
|---|---|
| https://github.com/NodeBB/NodeBB/blob/v4.13.2/src/activitypub/mocks.js | Exploit Third Party Advisory |
| https://github.com/bikini/exploitarium/tree/main/nodebb-activitypub-attributedto-local-uid-spoof-poc | Exploit Third Party Advisory |
| https://www.vulncheck.com/advisories/nodebb-activitypub-author-spoofing-via-unvalidated-attributedto-mapped-to-local-user | Exploit Third Party Advisory |
Configurations
History
No history.
Information
Published : 2026-07-01 20:17
Updated : 2026-07-07 13:16
NVD link : CVE-2026-58593
Mitre link : CVE-2026-58593
CVE.ORG link : CVE-2026-58593
JSON object : View
Products Affected
nodebb
- nodebb