SillyTavern: Authentication Bypass via SSO Header Injection_CVE-2026-44649

9.8 / 10

CRITICAL

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

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.

Basic Information

ID CVE-2026-44649

Source GitHub_M

Published May 29, 2026 at 17:45

Affected Product

Vendor SillyTavern

Product SillyTavern

Version < 1.18.0

Affected Versions SillyTavern SillyTavern < 1.18.0

CWE Classification

CWE-290 CWE-306 CWE-346 CWE-807

References

github.com /SillyTavern/SillyTavern/security/advisories/GHSA-gxx6-h3g6-vwjh

{
    "lastseen": "",
    "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.",
    "published": "2026-05-29T17:45:26.073Z",
    "modified": "2026-05-29T17:45:26.073Z",
    "type": "cve",
    "title": "SillyTavern: Authentication Bypass via SSO Header Injection",
    "source": "GitHub_M",
    "references": "https://github.com/SillyTavern/SillyTavern/security/advisories/GHSA-gxx6-h3g6-vwjh",
    "id": "CVE-2026-44649",
    "bulletinFamily": "",
    "cwe": [
        "CWE-290",
        "CWE-306",
        "CWE-346",
        "CWE-807"
    ],
    "cvelist": null,
    "sourceData": "SillyTavern SillyTavern < 1.18.0",
    "sourceHref": "",
    "cvss": {
        "score": 9.8,
        "severity": "CRITICAL",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "SillyTavern",
    "version": "< 1.18.0",
    "vendor": "SillyTavern",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}