---
title: 'New anomaly signal: INSECURE-DESER'
summary: null
url: >-
  https://www.fastly.com/documentation/reference/changes/2026/10/added-ngwaf-attack-signal
---

The [Insecure Deserialization](https://www.fastly.com/documentation/guides/next-gen-waf/signals/using-system-signals/#anomalies-insecure-deser) (`INSECURE-DESER`) anomaly signal is now generally available. Originally released through [Fastly Security Labs](https://www.fastly.com/documentation/guides/next-gen-waf/fastly-security-labs), this signal detects attempts to exploit unsafe deserialization of data. On-Prem WAF deployments require an agent running version 4.77.0 or higher.

Note that this signal will be converted to an [attack signal](https://www.fastly.com/documentation/guides/next-gen-waf/signals/using-system-signals/#attacks) at a future date.