CVE-2026-58593

NodeBB - ActivityPub Author Spoofing via Unvalidated attributedTo Mapped to Local User

HIGH
7.5
CVSS Score
Published: July 1, 2026 at 07:27 PM UTC
Updated: July 7, 2026 at 01:16 PM UTC
1 product affected across 1 vendorNodeBB

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Severity
HIGH7.5
Exploit prediction
EPSS 0.3%
SSVC
PoC

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≤ 4.13.24.13.2

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-345CWE-290

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