n8n CVE-2026-118641

Requires an n8n instance (vulnerable: <1.123.85, 2.x <2.43.5, or 2.44.x <2.44.1) running a workflow that uses the Microsoft Outlook contact getAll operation or the Microsoft SharePoint v1 item update/upsert operation AND that expression-binds untrusted external data (e.g. webhook or form input) into the affected $filter-backed parameter. This binding is the specific precondition reflected by AT:P - an instance with no such workflow, or one that only passes trusted/static values into those fields, is not exploitable. Impact is further limited to the scope of the stored Microsoft 365 credential: an attacker can read that mailbox's contacts or redirect writes within that SharePoint site, not escalate beyond the credential's permissions. Mitigations per the vendor: upgrade (the only complete fix), restrict instance access to trusted users, audit/remove untrusted bindings into these operations, apply network controls on feeding webhook endpoints, or deactivate affected workflows until patched.

This is a medium-severity, conditionally-exploitable issue rather than a drop-everything emergency. The input's CVSS 4.0 vector (6.9) shows AV:N/AC:L/PR:N/UI:N - network-reachable with no authentication or user interaction - but crucially includes AT:P, meaning a specific attack precondition must exist: a workflow must bind untrusted external input into the affected OData $filter parameter. Impact is real but bounded: VC:L to the n8n node and SC:H to the connected Microsoft 365 tenant (dumping an entire mailbox contact list), plus SI:L integrity impact from redirecting SharePoint writes, all confined to the stored credential's scope. The vuln.today decision label is 'this_month', not 'act_now' or 'emergency', which is consistent with the moderate score. No EPSS score was supplied, the CVE is NOT in CISA KEV, and no public exploit code is referenced - only vendor/coordinator advisories (GHSA, VulnCheck). Net: a legitimate issue to patch on a normal cycle, not a high-CVSS-but-no-substance finding, but also not evidence of widespread active exploitation. The 'Microsoft' vendor tag is misleading - the affected product is the open-source n8n automation platform, not a Microsoft product (see data_quality_flags).

An n8n workflow exposes a webhook (or other external trigger) whose input is expression-bound into the Microsoft Outlook contact getAll $filter or the SharePoint v1 item update pre-write lookup. An attacker submits a value containing a single quote, closing the OData string literal and rewriting the query, so the Outlook node returns the bound mailbox's entire contact list instead of one match, or the SharePoint write is redirected onto an unintended list item within the stored credential's scope. No public exploit code is identified at time of analysis; the attack requires that a vulnerable workflow actually passes untrusted input into these fields.