n8n EUVD-2026-112380

Requires an authenticated n8n member account with permission to create and run workflows (PR:L, confirmed by CVSS vector), and the instance must use the Data Tables module. The attacker creates a workflow whose client-supplied ID is the literal string '__proto__', which makes the cached owner-project check match every project and grants cross-project Data Table row access. Limiting factors: exploitation is not possible for fully unauthenticated users, is irrelevant on single-trusted-user instances, and is neutralized by disabling the Data Tables module; affected versions are n8n before 2.43.5 and 2.44.x before 2.44.1.

This is a genuine priority, not an inflated-CVSS artifact. The CVSS 4.0 base score of 8.7 (High) is driven by a fully network-reachable attack path (AV:N), low complexity (AC:L), no attack requirements (AT:N), and no user interaction (UI:N), with high confidentiality and integrity impact (VC:H/VI:H) plus limited availability impact (VA:L) from the ability to delete Data Table rows. The one meaningful brake is PR:L - exploitation requires an authenticated member who can create and run workflows, so this is an insider / compromised-account / shared-tenant risk rather than a pre-auth internet-facing break. EPSS is not supplied and the issue is not on CISA KEV, so there is no quantitative exploitation-probability signal and no confirmation of active exploitation; the vuln.today decision label is 'this_week', consistent with a serious but non-emergency flaw. The mechanism is well understood and documented by the vendor (CWE-1321 prototype pollution via a client-supplied workflow ID of __proto__ corrupting the Data Table owner-project check), which lowers the research barrier for a working exploit even though none is confirmed public. Net: on multi-tenant or multi-user n8n instances this warrants prompt patching; on single-trusted-user deployments the PR:L requirement materially reduces real-world urgency.

An authenticated n8n member on a shared instance creates a workflow and supplies the crafted ID '__proto__', which pollutes the in-memory owner-project cache so the Data Table project authorization check matches every project. The member then runs workflow operations to list, read, modify, and delete Data Table rows belonging to projects they should have no access to. No public working exploit is confirmed, but the vendor advisory describes the trigger precisely.