n8n CVE-2026-110846

Exploitation requires that the attacker possess a valid resume token for an existing Send-and-Wait (waiting) execution - this is the explicit AT:P attack requirement and the primary limiting factor; an attacker with no access to a resume token cannot trigger the bypass. The affected feature is specifically the waiting-webhook endpoint used by n8n's Send-and-Wait / human-approval nodes, so only workflows that use waiting executions are exposed. Given PR:N in the CVSS vector, no account authentication to n8n itself is needed beyond holding the token, and no user interaction is required. Realistic impact is bounded by what the target workflow's downstream nodes do under the owner's credentials - command execution is possible only where the workflow is configured to perform such actions. Affects n8n before 2.41.4 and 2.42.x before 2.42.1.

This is a credible, moderate-to-high priority issue for organisations running n8n, but not a drop-everything emergency. The authoritative signal is the CVSS 4.0 vector (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:H/SI:H/SA:N, base 7.0), which indicates a network-reachable, low-complexity flaw requiring no authentication (PR:N) and no user interaction (UI:N), but carrying an explicit Attack Requirement (AT:P) - the attacker must already hold a valid execution resume token. Vulnerable-system impact is only Low/Low (VC:L/VI:L), yet the subsequent-system impact is High/High (SC:H/SI:H): approving a waiting execution runs downstream actions under the workflow owner's credentials, potentially reaching command execution. That gap between low direct impact and high downstream impact is the real story - the bug's danger comes from privilege inheritance, not from the endpoint itself. No EPSS score, no CISA KEV listing, and no public POC were supplied, so there is no evidence of active exploitation or widespread automated attack; the AT:P token prerequisite also argues against mass, indiscriminate exploitation and toward targeted abuse by someone who can obtain or intercept resume tokens. CWE-180 (validate-before-canonicalize) is consistent with the description's 'selects validation before normalising an alternate node reference form.' Net: a genuine privilege/signature-bypass worth prompt patching, tempered by the token precondition and the absence of exploitation telemetry.

An attacker who has obtained a valid resume token for a Send-and-Wait execution (for example, a leaked or intercepted approval link intended for another approver) sends a crafted request to the waiting-webhook endpoint using an alternate node reference form that bypasses the HMAC signature check. The endpoint approves the execution and runs its downstream nodes under the workflow owner's stored credentials, potentially triggering command execution. No public exploit identified at time of analysis, and exploitation is gated on possessing a resume token.