Google previews Agent Anomaly Detection to catch hijacked AI agents

Google opened a private preview of Agent Anomaly Detection on the Gemini Enterprise Agent Platform, a monitor that flags AI agent sessions showing signs of goal hijacking.

Google announced a private preview of Agent Anomaly Detection (AAD) on the Gemini Enterprise Agent Platform. The announcement, authored by Nakul Javali, appeared on November 12, 2026 on the Google Developers Blog. AAD is an asynchronous monitor that reads an agent's traces and logs after execution to flag sessions where the agent strayed outside its intended behavior.

What Google is rolling out

AAD is available in Private Preview on the Gemini Enterprise Agent Platform and analyzes agent traces and logs asynchronously, adding no runtime latency.
It targets goal hijacking, which Google says ranks #1 in the OWASP Agentic Top 10 for 2026.
Google evaluated AAD on 1,774 sessions across five public benchmarks: AgentDojo, InjecAgent, Agent Security Bench, AgentDyn and AgentHarm, using gemini-2.5-flash with the Agent Development Kit (ADK) as the agent under test.
AAD flagged 87% of harmful instructions the agent actually executed overall, with per-benchmark detection of 85% on AgentDojo, 87% on InjecAgent, 99% on AgentDyn and 81% on AgentHarm.
False-positive rates stayed at 2 to 4% on injection benchmarks but rose to 16% on AgentHarm.
AAD caught only 4 of 18 simulated long-term memory-poisoning attacks.

What it means for people who build with AI

As companies move autonomous agents into production, a monitoring layer that retroactively flags hijacked or misbehaving sessions addresses goal hijacking, the risk Google says sits at the top of the OWASP Agentic Top 10 for 2026. The benchmark numbers show real detection power on injection-style attacks, but Google's own results also show AAD still misses most long-term memory-poisoning attempts, so teams building agents should not treat it as a complete defense.

Availability

Agent Anomaly Detection is currently limited to Private Preview on the Gemini Enterprise Agent Platform, and access requires submitting a request through that platform.

Sources

How Agent Anomaly Detection scores on benchmarks we didn't write (Google Developers Blog, November 12, 2026, official)

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