Vulnerability · Published May 29, 2026 · Assigned by GitHub_M
CVE-2026-44649SillyTavern: Authentication Bypass via SSO Header Injection
Critical 9.8
In plain English
A critical-severity authentication bypass by spoofing in SillyTavern from SillyTavern. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | sillytavern | 1.18.0 | GHSA-gxx6-h3g6-vwjh |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| SillyTavern | SillyTavern | < 1.18.0 |
Weakness: CWE-290, CWE-306, CWE-346, CWE-807 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H