CVE-2026-44649: Sillytavern

Critical severity, CVSS 9.8. EPSS: 0.3% chance of exploitation in the next 30 days.

SillyTavern is a locally installed user interface that allows users to interact with text generation large language models, image generation engines, and text-to-speech voice models. Prior to 1.18.0, SillyTavern accepts Remote-User (Authelia) and X-Authentik-Username (Authentik) HTTP headers to automatically log in users when SSO is configured. There is no validation that these headers originate from a trusted reverse proxy. Any network client that can reach the SillyTavern port directly can inject these headers and authenticate as any user, including administrators, without a password. This vulnerability is exploitable only when sso.autheliaAuth: true or sso.authentikAuth: true is set in config.yaml (both default to false). This vulnerability is fixed in 1.18.0.

Affected products

• Sillytavern Sillytavern: before 1.18.0 (fixed in 1.18.0)

Published 2026-05-29. Last modified 2026-07-22.