CVE-2026-44649Public exploitNetwork attack vector

Unauthenticated account takeover via SSO header injection

Published May 29, 2026 · Updated May 29, 2026

Authentication bypass in SillyTavern before 1.18.0 allows remote attackers to take over any account through forged SSO headers. The tryAutoLogin flow calls headerUserLogin for /login, which trusts client-supplied Remote-User or X-Authentik-Username values and creates a matching user's session without verifying the sender's proxy address. Exploitation requires sso.autheliaAuth or sso.authentikAuth to be enabled and direct network access to the application port; both settings are disabled by default, while a successful request grants the targeted user's privileges, including administrator access.

CVSS severity9.8
Critical
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in SillyTavern before 1.18.0 allows remote attackers to take over any account through forged SSO headers. The tryAutoLogin flow calls headerUserLogin for /login, which trusts client-supplied Remote-User or X-Authentik-Username values and creates a matching user's session without verifying the sender's proxy address. Exploitation requires sso.autheliaAuth or sso.authentikAuth to be enabled and direct network access to the application port; both settings are disabled by default, while a successful request grants the targeted user's privileges, including administrator access.

The record

CVE
CVE-2026-44649
Published
May 29, 2026
Updated
May 29, 2026
Vendor
SillyTavern
Product
SillyTavern
Classifications
CWE-807, CWE-306, CWE-290, CWE-346, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 29, 2026CVE publishedPublication date reported by the CVE source.
  2. May 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.18.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SillyTavern · SillyTavernversion=< 1.18.0

Published CVSS scores

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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-807Reliance on Untrusted Inputs in a Security Decision
CWE-306Missing Authentication for Critical Function
CWE-290Authentication Bypass by Spoofing
CWE-346Origin Validation Error
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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