SillyTavern: Authentication Bypass via SSO Header Injection

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Summary

CVECVE-2026-44649
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-29 19:16:24 UTC
Updated2026-06-02 03:16:17 UTC
DescriptionSillyTavern 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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000670000 probability, percentile 0.207600000 (date 2026-06-01)

Problem Types: CWE-290 | CWE-306 | CWE-346 | CWE-807 | CWE-290 CWE-290: Authentication Bypass by Spoofing | CWE-306 CWE-306: Missing Authentication for Critical Function | CWE-346 CWE-346: Origin Validation Error | CWE-807 CWE-807: Reliance on Untrusted Inputs in a Security Decision

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA SillyTavern SillyTavern affected < 1.18.0 Not specified

References

ReferenceSourceLinkTags
github.com/SillyTavern/SillyTavern/security/advisories/GHSA-gxx6-h3g6-vwjh 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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