CVE-2026-86077: n8n: Anonymous Approval-Gate Bypass via Reused resumeToken over the Chat WebSocket

Workflow authors put approval gates (human-in-the-loop steps) in front of actions too consequential to automate. n8n gives a resume token to anonymous people who submit a Form Trigger. The /chat WebSocket route accepted that token and resumed the paused execution. It did not check that the paused node was a chat-capable node. This is a missing authorization check (CWE-862).

An attacker needs no account. They submit the public form, keep the token, and present it on the chat route. The execution then continues past a Send-and-Wait, Telegram, Slack or Gmail approval step, or a plain Wait node, without the approver's decision. What happens next depends on the workflow: it may send a message, change records or call a paid API.

The CVSS vector rates confidentiality and integrity impact as low, because the attacker only advances the workflow and does not choose its content. Public-facing instances that combine a Form Trigger with a non-chat approval gate carry the real risk. The patch restricts resume over the chat route and Chat Hub to chat-capable node types.

Affected: n8n from 2.38.0 up to but not including 2.38.2, and every release below 2.37.7. The exposed pattern is a workflow that starts from a Form Trigger and later waits at a non-chat approval gate, on an instance reachable by outsiders. Check the version:

npm ls n8n

For Docker installs, check the image tag or the version shown in the n8n UI.

Upgrade to 2.37.7 or 2.38.2, or later:

npm install -g [email protected]

The advisory lists stopgaps that it says do not fully remediate the risk:

• Limit n8n instance access to fully trusted users.
• On public instances, avoid workflows that combine a Form Trigger with non-chat approval gates (Send-and-Wait, Telegram/Slack/Gmail HITL, or plain Wait nodes).
• Audit recent executions of such workflows for unexpected completion without a matching approval callback.

List executions of workflows that have a Form Trigger followed by a Wait or approval node. Look for executions that finished with no matching approval callback, such as a missing Slack or Telegram response or no Send-and-Wait reply. Check access logs for WebSocket upgrades to /chat from clients that never used the chat feature. The advisory names the audit of unexpected completions as its detection hint and gives no other indicators.

Impact

The /chat WebSocket route resumed a paused execution from a resume token without checking that the node being resumed was a chat node. n8n hands that token to anonymous form submitters, so a party with no account could present it on the chat route and release an execution waiting at an approval gate, the control an author puts in front of an action considered too consequential to automate. The patch restricts resume over the chat route and Chat Hub to chat-capable node types.

Patches

The issue has been fixed in n8n versions 2.37.7 and 2.38.2. Users should upgrade to one of these versions or later to remediate the vulnerability.

Workarounds

If upgrading is not immediately possible, administrators should consider the following temporary mitigations:

• Restrict n8n instance access to fully trusted users only.
• Avoid workflows that combine a Form Trigger with non-chat approval gates (Send-and-Wait, Telegram/Slack/Gmail HITL, or plain Wait nodes) on publicly accessible instances.
• Audit recent executions of such workflows for unexpected completion without a corresponding approval callback.

These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.