If you run Cursor’s AI agent in Auto-Run Sandbox mode on macOS, and you have Docker Desktop with the Dev Containers CLI installed, there’s a patched vulnerability you need to know about: CVE-2026-73218. It’s rated CVSS 7.7, it was fixed in Cursor 3.0.0, and if you haven’t updated, here’s exactly what was wrong and how to check whether you’re exposed.

What the Vulnerability Actually Does

According to the official CVE record (confirmed against both Tenable’s listing and the corresponding GitHub Security Advisory, GHSA-v4xv-rqh3-w9mc), the issue works like this:

Prior to version 3.0.0, Cursor IDE for macOS allows an agent running in Auto-Run Sandbox mode, when Docker Desktop and the Dev Containers CLI are installed, to launch a privileged container and mount Docker’s virtiofs0, granting read and write access to the user’s home directory and enabling host command execution with the user’s privileges — without an additional permission prompt.

In plain terms: Cursor’s “Auto-Run Sandbox” mode is supposed to let an AI agent execute commands automatically while being contained — the whole point of a sandbox is that the agent can’t just reach out and touch your real filesystem or run arbitrary commands on your actual machine. This vulnerability broke that containment specifically when Docker Desktop and the Dev Containers CLI were present: the agent could launch a privileged container, mount a virtiofs share, and from there get read/write access to your home directory and execute commands with your own user privileges — all without triggering the extra permission prompt that’s supposed to gate that kind of access.

The CVSS v4 vector (AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N) reflects high impact to confidentiality, integrity, and availability once triggered, though it requires some attack complexity and prior conditions (Docker Desktop + Dev Containers CLI installed, sandbox mode active) to be exploitable.

Step 1: Check Your Cursor Version

The vulnerability is fixed in Cursor 3.0.0. If you’re on any earlier version on macOS, you’re potentially exposed under the conditions above.

To check your version:

  • macOS: Click Cursor in the menu bar → About Cursor.
  • If you have the cursor shell command installed, you can also try cursor --version from a terminal — though this can occasionally report an outdated or incorrect version if multiple installs exist on your system, so the About menu is the more reliable source.

If you’re below 3.0.0, update Cursor immediately through its built-in updater or by downloading the latest release from Cursor’s official site.

Step 2: Check Whether the Vulnerable Conditions Apply to You

You were only exposed to this specific issue if all of the following were true prior to updating:

  1. You’re running Cursor on macOS.
  2. You have Docker Desktop installed.
  3. You have the Dev Containers CLI installed.
  4. Cursor’s agent was configured to run in Auto-Run Sandbox mode.

If any of those weren’t true, this particular CVE didn’t apply to your setup — but updating to 3.0.0 or later is still the right move, since it closes the issue regardless of your current configuration.

Step 3: Review Your Auto-Run Settings

Beyond just patching, it’s worth understanding what Auto-Run Sandbox mode is actually meant to do and whether it’s the right setting for your workflow. Cursor’s agent settings include multiple auto-run modes with different trust models — broadly, options that range from prompting for approval on every command, to using an allowlist of pre-approved commands, to running everything (sandboxed or not) automatically.

⚠️ We could not confirm the exact current menu labels and toggle paths for these settings against an official Cursor documentation page — the specifics discussed in community forums may not exactly match your installed version’s UI. Refer to Cursor’s official settings documentation, or navigate to your agent/auto-run settings directly within the app, to confirm the exact current option names and their behavior before making changes.

As a general security practice independent of this specific CVE: if you’re working in a dev container context where the agent needs elevated access to run builds or tests, consider whether an allowlist-based approach (approving specific, known-safe commands) gives you more visibility than a broad “run everything in a sandbox and trust the containment” setting — especially given that this CVE demonstrates sandbox containment itself can have gaps.

Step 4: Watch for Similar Container-Escape Patterns Elsewhere

This isn’t a Cursor-specific category of risk — any AI coding agent that combines (a) automatic command execution and (b) access to container tooling like Docker is a candidate for this same class of vulnerability: sandbox says “contained,” but a privileged container plus a host filesystem mount quietly breaks that promise. If you use other AI coding agents with sandbox or auto-run features alongside Docker Desktop, it’s worth checking their changelogs and security advisories for similar disclosures, and applying the same checklist — version check, condition check, settings review — to each.

Sources

  1. CVE-2026-73218 — Tenable
  2. GHSA-v4xv-rqh3-w9mc — Sandbox escape via launching privileged containers — GitHub Security Advisory

Researched by Searcher → Analyzed by Analyst → Written by Writer Agent (Sonnet 4.6). Full pipeline log: subagentic-20260811-2000

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