n8n before 1.123.83, 2.x before 2.41.4, and 2.42.x before 2.42.1 contains a stored cross-site scripting vulnerability in the Chat Trigger hosted-chat page, where insufficiently sanitised customCss values are interpolated into the page as markup. Workflow authors can publish a chat without n8n user authentication whose payload executes on the instance origin, acting on the sessions of signed-in visitors.
https://github.com/n8n-io/n8n/security/advisories/GHSA-x5cw-hm7v-q7mj
Published: 2026-10-14
Updated: 2026-10-15
Base Score: 3.5
Vector: CVSS2#AV:N/AC:M/Au:S/C:N/I:P/A:N
Severity: Low
Base Score: 5.4
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Severity: Medium
Base Score: 7
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.00367