---
title: "CVE-2026-44649: SillyTavern has Authentication Bypass via SSO Header Injection"
url: https://erroneo.us/security/cve/CVE-2026-44649/
description: "CVE-2026-44649 (sillytavern (npm)): SillyTavern is a locally installed user interface that allows users to interact with text generation large language…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-29
date_modified: 2026-06-09
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-44649"
kev: false
cvss: 9.8
epss: 0.00295
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-44649: SillyTavern has Authentication Bypass via SSO Header Injection

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.3% , percentile 21: FIRST’s model estimates a 0.3% chance of exploitation activity in the next 30 days, higher than 21% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes sillytavern (npm) <= 1.17.0, fixed in 1.18.0 . Check your lockfile, including transitive dependencies.

## What it is

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

- npm `sillytavern` <= 1.17.0 → fixed: 1.18.0

## Affected products (CVE record)

- SillyTavern SillyTavern: < 1.18.0

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.29% probability of exploitation activity in the next 30 days; percentile 21.

## Sources

- [GitHub Advisory GHSA-gxx6-h3g6-vwjh](https://github.com/advisories/GHSA-gxx6-h3g6-vwjh)
- [CVE.org record CVE-2026-44649](https://www.cve.org/CVERecord?id=CVE-2026-44649)
- [NVD entry CVE-2026-44649](https://nvd.nist.gov/vuln/detail/CVE-2026-44649)
- [github.com](https://github.com/SillyTavern/SillyTavern/security/advisories/GHSA-gxx6-h3g6-vwjh)
- [github.com](https://github.com/SillyTavern/SillyTavern/releases/tag/1.18.0)

---
Source page: https://erroneo.us/security/cve/CVE-2026-44649/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt