SillyTavern has Authentication Bypass via SSO Header Injection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-44649: 0.22% estimated exploitation activity in the next 30 days; percentile 12.31 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Resolution SillyTavern 1.18.0 now includes a configuration option to limit which IP addresses can authorize using SSO headers, limiting to just loopback addresses by default. A setting can be customized according to user's needs. Documentation: https://docs.sillytavern.app/administration/sso/ Summary 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). Detials SillyTavern implements header-based SSO for Authelia and Authentik. When enabled, the tryAutoLogin function (called on every request to /login) invokes…

Published by the source

12 May 2026, 22:23 UTC

Last modified by the source

9 Jun 2026, 10:45 UTC

Source last checked

26 Oct 2026, 12:53 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-gxx6-h3g6-vwjh

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-gxx6-h3g6-vwjh

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-gxx6-h3g6-vwjh

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-44649

Advisory: SillyTavern has Authentication Bypass via SSO Header Injection
IDs: CVE-2026-44649, GHSA-gxx6-h3g6-vwjh
Record: https://patchnext.com/advisories/cve-2026-44649 (revision 3, source checked 26 Oct 2026, 12:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: sillytavern 1.18.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm sillytavern: affected <= 1.17.0; fixed in 1.18.0

## Suggested inspection (read-only)
- `npm ls sillytavern --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on sillytavern.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-gxx6-h3g6-vwjh (GitHub-reviewed advisory GHSA-gxx6-h3g6-vwjh lists affected ranges: npm sillytavern >=0 <=1.17.0)
- Verified: https://osv.dev/vulnerability/GHSA-gxx6-h3g6-vwjh (OSV record GHSA-gxx6-h3g6-vwjh lists affected ranges: npm sillytavern >=0 <1.18.0 (fixed))

Commands are suggestions: review each one before running it.