CVE-2026-54047

Laci Synchroni is a decentralized mod and appearance sync server and plugin for Dalamud. Versions of the backend prior to 1.2.3 have an improper authentication vulnerability in the application's OAuth2 login flow. The application relies on client-side state by trusting the `UID` field inside the `Authentications` object of a user's local `config.json` file. By manually editing this local file on their PC prior to logging in, a user can supply an arbitrary UID. Because the server fails to validate that the authenticated OAuth2 identity matches the requested UID, an attacker can fully impersonate any target user and perform actions on their behalf. This issue has been resolved in version 1.2.3. The patch modifies `AuthorizeOauthAsync` inside the `SecretKeyAuthenticatorService` to strictly bind the lookup of the requested User ID (`requestedUid`) to the record of the successfully authenticated identity (`primaryUid`). The server will no longer load or return session tokens for a requested UID unless it matches the verified, authenticated database record. No known workarounds are available.

CVSS

No CVSS.

References

Link	Resource
https://github.com/LaciSynchroni/server/commit/5bc3efd68b738328b8faeff089dd18a826ec9ca4
https://github.com/LaciSynchroni/server/pull/28
https://github.com/LaciSynchroni/server/releases/tag/v1.2.3
https://github.com/LaciSynchroni/server/security/advisories/GHSA-gq4p-pxvg-6x9j

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-11 17:17

Updated : 2026-09-11 20:17

NVD link : CVE-2026-54047

Mitre link : CVE-2026-54047

CVE.ORG link : CVE-2026-54047

JSON object : View

Products Affected

No product.

CWE

CWE-287

Improper Authentication

CWE-349

Acceptance of Extraneous Untrusted Data With Trusted Data

CWE-602

Client-Side Enforcement of Server-Side Security

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