7.5

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-44648

CVE-2026-44648: SillyTavern: Existing sessions are not invalidated after password change, allowing session reuse and account takeover

Summary

Changing a user’s password does not invalidate existing sessions, allowing an attacker with a stolen cookie to retain access even after the victim resets their password.

Details

SillyTavern relies on cookie-session for authentication, storing all session data (user handle, permissions) in a signed cookie. The endpoints POST /api/users/change-password and POST /api/users/recover-step2 only update the password hash in the database but do not expire current sessions. Because the session is stateless and stored entirely in the client cookie, there is no server-side mechanism to revoke a token once issued.

PoC

1.Log into the same SillyTavern account from two different browsers (e.g., Chrome and Firefox private mode). 2.In Chrome, change the account password under User Settings → Change Password. 3.In Firefox, refresh the page or perform a protected action (e.g., view API keys). 4.Expected: Firefox session should be invalidated and ask for login. 5.Actual: Firefox remains fully authenticated, able to perform all actions as the targeted user.

Impact

An attacker who obtains a valid session cookie (via XSS, MITM, physical access, etc.) can continue using it indefinitely, even after the legitimate user changes their password. This nullifies the most common recovery measure against session theft. The default cookie lifespan is 400 days, giving an attacker a very long exploitation window.

Resolution

A fix was released in the version 1.18.0, invalidating a session cookie on account password change.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2026-44648

CVE-2026-44648:

7.5

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
sillytavern	npm	<= 1.17.0	1.18.0

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability lies in the fact that SillyTavern did not invalidate existing user sessions after a password change or recovery. This allowed an attacker with a stolen session cookie to maintain access to the user's account even after the user had changed their password. The root cause was the stateless nature of the sessions, which were stored entirely in client-side cookies without a server-side mechanism for revocation.

The fix, introduced in version 1.18.0, implements a session versioning system. A new function, getAccountVersion, generates a version tag based on the user's handle, password hash, and salt. This version tag is stored in the session cookie upon login, password change, and password recovery.

A middleware, setUserDataMiddleware, is now executed on every authenticated request. This middleware compares the version tag in the session cookie with the current version tag of the user account. If they do not match, it means the user's credentials have changed (e.g., a password update), and the session is invalidated, forcing a re-login.

The vulnerable functions are the ones that handle password changes but failed to invalidate sessions. The analysis of the patch identified two such functions:

The anonymous function handling the POST /api/users/change-password route in src/endpoints/users-private.js.
The anonymous function handling the POST /api/users/recover-step2 route in src/endpoints/users-public.js.

These functions were modified in the patch to update the session with the new account version, thus ensuring that any other sessions with an older version become invalid. The setUserDataMiddleware is the enforcement point for this new security measure.

Vulnerable functions

router.post('/change-password')

src/endpoints/users-private.js

This function handles the password change functionality. Before the patch, it did not invalidate existing sessions, allowing an attacker with a stolen session cookie to maintain access even after the user changed their password. The patch introduces a session versioning mechanism, and this function was updated to set the new version, effectively invalidating older sessions.

router.post('/recover-step2')

src/endpoints/users-public.js

This function handles the second step of password recovery, which includes setting a new password. Similar to the password change function, it did not invalidate existing sessions before the patch. An attacker could retain access using a stolen session even after the user recovered their account and set a new password. The patch added session versioning to this flow to fix the issue.

setUserDataMiddleware

src/users.js

This middleware is executed for authenticated routes. Before the patch, it did not perform any session validation based on password changes. The vulnerability was not in this function itself, but in the absence of the logic that the patch introduced. The patch modified this function to check a session version on every request, invalidating sessions if the password has been changed. This is the function that now enforces the security measure that was previously missing.

Vulnerability Intelligence
Miggo AI

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WAF Protection Rules

WAF Rule

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Reasoning

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