CVE-2026-86077 Overview
CVE-2026-86077 is a missing authorization vulnerability [CWE-862] in n8n, an open source workflow automation platform. Versions prior to 2.37.7 and 2.38.2 expose a flaw in the /chat WebSocket route that fails to validate whether the target node supports chat messages before resuming a paused workflow execution. An anonymous form submitter who obtains a resumeToken can reuse it against the chat route to release a Send-and-Wait, non-chat Human-In-The-Loop (HITL), or Wait approval gate that was never intended to be resumed through chat.
Critical Impact
Unauthenticated attackers can bypass workflow approval gates and prematurely release paused executions, subverting business logic controls in automated workflows.
Affected Products
- n8n versions prior to 2.37.7 (2.37.x branch)
- n8n versions prior to 2.38.2 (2.38.x branch)
- Self-hosted and cloud n8n workflow automation deployments
Discovery Timeline
- 2026-09-08 - CVE-2026-86077 published to NVD
- 2026-09-09 - Last updated in NVD database
Technical Details for CVE-2026-86077
Vulnerability Analysis
The vulnerability resides in the chat execution manager component at packages/cli/src/chat/chat-execution-manager.ts. The canResumeOverChat authorization function fails to verify that the resume target node actually supports chat messages before allowing a resume operation. This omission enables cross-mechanism resumption of paused workflow executions.
When an n8n workflow contains a paused node awaiting external input, the platform issues a resumeToken for that execution. This token is scoped to a particular resume mechanism such as form submission, Send-and-Wait, HITL, or Wait approval. The /chat WebSocket route accepts the token without checking whether the target node was designed to accept chat-based resumption.
Root Cause
The root cause is a missing authorization check [CWE-862] in the canResumeOverChat function. The function grants resume permission based solely on token validity rather than verifying node-type compatibility. Broken access control at the resume gate allows an actor holding a form-scoped token to trigger workflow continuation through an unrelated chat interface.
Attack Vector
An anonymous user submits a form that returns a resumeToken intended for form-based resumption. The attacker then connects to the /chat WebSocket endpoint and replays the token to release approval gates on Send-and-Wait, non-chat HITL, or Wait nodes. The attack requires no authentication and can be executed remotely over the network against any reachable n8n instance running a vulnerable version.
The vulnerability mechanism is described in the GitHub Security Advisory GHSA-35jj-42hp-8gmq. No public proof-of-concept exploit code has been released.
Detection Methods for CVE-2026-86077
Indicators of Compromise
- Unexpected WebSocket connections to the /chat route from external or anonymous sources
- Workflow executions resumed from non-chat nodes such as Send-and-Wait, Wait, or HITL through the chat channel
- Approval gates released without corresponding legitimate approver activity in audit logs
- Reuse of the same resumeToken value across different resume endpoints within a short time window
Detection Strategies
- Review n8n execution logs for resume events on Send-and-Wait, Wait, and HITL nodes that originated from the chat WebSocket transport
- Correlate resumeToken issuance events with the endpoint used to consume them and flag mismatches between issuing node type and consuming route
- Enable verbose logging on the packages/cli/src/chat/chat-execution-manager.ts code path to capture resume attempts and target node metadata
Monitoring Recommendations
- Instrument the /chat WebSocket endpoint with request-level telemetry including source IP, token identifier, and target execution ID
- Alert on workflow completions that skip expected approval durations, indicating premature gate release
- Forward n8n application logs to a centralized analytics platform to enable historical review and correlation across executions
How to Mitigate CVE-2026-86077
Immediate Actions Required
- Upgrade n8n to version 2.37.7 on the 2.37.x branch or 2.38.2 on the 2.38.x branch
- Audit existing workflows containing Send-and-Wait, HITL, or Wait nodes for signs of unauthorized resumption
- Restrict network exposure of the n8n /chat WebSocket endpoint to trusted networks where feasible
- Rotate any active resumeToken values by cancelling and reissuing paused executions after patching
Patch Information
The issue is fixed in n8n releases n8n@2.37.7 and n8n@2.38.2. The patch updates canResumeOverChat in packages/cli/src/chat/chat-execution-manager.ts to verify that the resume target node supports chat messages before allowing the operation.
Workarounds
- Place the n8n instance behind a reverse proxy that blocks or authenticates access to the /chat WebSocket route
- Avoid using Send-and-Wait, non-chat HITL, and Wait approval gates in workflows exposed to anonymous form submitters until patching is complete
- Apply strict network segmentation so that workflow instances handling sensitive approvals are not reachable from untrusted networks
# Upgrade n8n via npm to a fixed release
npm install -g n8n@2.38.2
# Verify the installed version
n8n --version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
