Vanta has signed a definitive agreement to buy Pillar Security, a startup that tests and guards AI agents, the two companies announced on November 9, 2026. The Pillar Security acquisition gives Vanta, which sells security and compliance software, a way to stop an agent’s action while it runs instead of only recording the policy the agent was supposed to follow.

Neither Vanta’s announcement nor Pillar’s own post gives a price or an expected closing date.

What Pillar does

Ziv Karliner and Dor Sarig founded Pillar Security in 2023. Karliner is chief executive; Vanta’s deal page lists Sarig as co-founder and chief product officer. Pillar’s software finds the AI applications and agents running inside a company, attacks them in tests the way an outsider would, and blocks actions they are not allowed to take while they run.

Two pieces of Pillar’s record come from the company itself:

  • Vulnerability research. Pillar says its researchers found flaws rated CVSS 10, including a sandbox escape in the n8n automation tool and a Gemini CLI flaw that let a single GitHub issue compromise the tool’s supply chain.
  • SAIL. Pillar’s framework for securing AI systems maps 91 AI risks across seven lifecycle phases. The company says it has passed 50,000 downloads.

The dates Vanta has given

Vanta plans to fold Pillar’s features into its platform through 2027, in this order:

  • January 2027: AI inventory. A map of the AI applications, models, agents, skills and MCP servers in a company, each tied to an owner, an approved use, the data it can reach, vendors, controls and risks.
  • January 2027: runtime monitoring and detection. Alerts on suspicious activity and guardrail violations.
  • Spring 2027: red teaming. Attack testing shaped to the customer’s own systems.
  • Summer 2027: runtime enforcement. Blocking an agent’s unauthorized action as it happens.

Vanta also says its AI governance product becomes a paid offering in January 2027. These are announced plans, not shipped features, and the later ones have only a season attached.

Why a compliance company wants a runtime tool

Compliance software has mostly dealt in evidence gathered after the fact: policies, control checks and audit records for frameworks such as SOC 2 and ISO 27001. An AI agent can break a rule in a single action between two reviews. Vanta’s example is an agent that tries to share sensitive financial information in an unapproved channel. In the combined product, the action is blocked, the Vanta Agent alerts the owner and an audit record shows which control fired.

The attacks Pillar tests for include instructions hidden in content an agent reads. Our explainer on prompt injection covers how that works, and the guide to what an AI agent can do with inbox access shows why the permissions an agent holds matter as much as the model.

The size figures in the announcement are Vanta’s own: more than 20,000 customers, up from 16,000 in the first quarter of 2026, and annual recurring revenue above $300 million, which it reported in April 2026. Pillar is Vanta’s third acquisition, after Trustpage in January 2023 and Riskey in July 2025.

What is not settled

  • Price and closing. Neither company has disclosed terms or said when the deal is expected to close.
  • Pillar as a separate product. The announcements describe Pillar’s features moving into Vanta. They do not say whether Pillar stays on sale to companies that do not use Vanta, so current customers should look for direct notice from the company.
  • Employee equity. The announcements do not say how Pillar shares and options are treated. Our explainers on employee stock options and vesting and tender offers cover the terms an employee of an acquired startup usually checks.