n8n versions before 1.123.73, 2.35.4, and 2.36.2 pass message content in the Gmail (v1) and Brevo nodes to the mail composer without verifying it is a string. An authenticated user able to run a workflow can supply an expression that resolves to an object carrying a path or href property, causing the composer to read a local file accessible to the n8n process or fetch an internal URL (SSRF) and attach the result to the outgoing message.
CVSS Details
- CVSS 4.0 Base Score: 7.1 (HIGH)
- CVSS 4.0 Vector: (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X)
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