In version 0.3.8 of open-webui, an endpoint for converting markdown to HTML is exposed without authentication. A maliciously crafted markdown payload can cause the server to spend excessive time converting it, leading to a denial of service. The server becomes unresponsive to other requests until the conversion is complete.
Severity
CVSS 3.0
7.5 high
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
0.9% chance of exploitation in the next 30 days; higher than 59% of CVEs (scores of 2026-10-31)