---
type: "Concept"
title: "Model poisoning & backdoors"
description: "Malicious participants corrupt the shared model."
tags: [fl, threat, security, federated]
generated: { by: human:crpage, at: 2026-07-09T09:44:00Z }
status: stable
---

Without strong node authentication, malicious or compromised participants can poison the shared model or implant backdoors. Access control and node identity matter as much as cryptography: if unauthorised participants can join, poisoning and replay risks remain.

Relates to: [Security and privacy of federation](../document/themes/uk-public-sector-implications.md), [SPIFFE/SPIRE](../standards/spiffe-spire.md).