EUVD-2026-33402
GHSA-wmm3-h9qj-p5v6
Severity by source
AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
AC:H and UI:R because exploitation needs a pre-stolen cookie plus a victim password change; PR:N as the attacker uses a stolen token, not credentials; C/I/A:H reflect full account takeover.
Primary rating from Vendor (https://github.com/SillyTavern/SillyTavern).
CVSS VectorVendor: https://github.com/SillyTavern/SillyTavern
Lifecycle Timeline
3DescriptionCVE.org
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.
AnalysisAI
Session persistence after credential change in SillyTavern before 1.18.0 lets an attacker holding a stolen session cookie retain full account access even after the victim resets their password. Because sessions are stateless and stored entirely in a signed client-side cookie with a default 400-day lifespan, the change-password and account-recovery endpoints update the password hash but never revoke outstanding tokens, defeating the standard remediation for cookie theft. No active exploitation is recorded (not in CISA KEV) and EPSS is very low at 0.02%, but public proof-of-concept reproduction steps are documented in the GHSA advisory.
Technical ContextAI
SillyTavern is a self-hosted Node.js/npm web frontend (pkg:npm/sillytavern) for interacting with large language models. It authenticates users via cookie-session, serializing all session state - user handle and permissions - into a single signed cookie rather than a server-side session store. This is the root cause of the flaw and maps to CWE-613 (Insufficient Session Expiration): because the token is self-contained and stateless, the server has no registry of issued sessions and therefore no mechanism to revoke one. The endpoints POST /api/users/change-password and POST /api/users/recover-step2 mutate only the stored password hash, so any previously issued cookie remains cryptographically valid and fully authorized until it naturally expires, which by default is 400 days out.
RemediationAI
Vendor-released patch: upgrade to SillyTavern 1.18.0 or later, which invalidates the session cookie on account password change (release: https://github.com/SillyTavern/SillyTavern/releases/tag/1.18.0). Because sessions are stateless, upgrading alone does not retroactively kill cookies already stolen before the upgrade, so after patching, rotate the session signing secret so all outstanding cookies are invalidated at once, then force all users to re-authenticate. As interim compensating controls on unpatched instances: reduce the session cookie lifespan from the 400-day default to a short window (trade-off: users must log in far more often); place SillyTavern behind a reverse proxy or VPN and restrict network exposure so cookie interception and remote reuse are harder (trade-off: added deployment complexity and remote-access friction); and if a compromise is suspected, rotate the cookie-signing secret to invalidate every existing session (trade-off: logs out all legitimate users). Also review the 1.18.0 hardening notes (rate limiting on basic auth, SSRF private-address whitelist, forwarded-IP header controls) as part of the same upgrade.
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External POC / Exploit Code
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