CVE-2026-58271

Sync-in Server is an open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.4.0, `POST /api/app/sync/register` accepts credentials and a TOTP code to register a desktop sync client. On a failed TOTP, `SyncClientsManager.register()` calls `updateAccesses(user, ip, false)`, which hits a freeze branch that writes `passwordAttempts` back unchanged. The counter never reaches `USER_MAX_PASSWORD_ATTEMPTS` (10) and the lockout gate never fires. A successful guess returns a `{clientId, clientToken}` pair. The token can be exchanged via `POST /api/app/sync/auth/cookie` for a full JWT. While the code is valid, the attacker can also call `POST /api/auth/2fa/disable` to permanently remove MFA. Version 2.4.0 patches the issue.

CVSS v3 6.8 MEDIUM

6.8^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.6 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/Sync-in/server/security/advisories/GHSA-274f-6w77-8qm9
https://github.com/Sync-in/server/security/advisories/GHSA-274f-6w77-8qm9

Configurations

No configuration.

History

24 Sep 2026, 23:17

Type	Values Removed	Values Added
References	~~() https://github.com/Sync-in/server/security/advisories/GHSA-274f-6w77-8qm9 -~~	() https://github.com/Sync-in/server/security/advisories/GHSA-274f-6w77-8qm9 -

21 Sep 2026, 20:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-09-21 20:17

Updated : 2026-09-24 23:17

NVD link : CVE-2026-58271

Mitre link : CVE-2026-58271

CVE.ORG link : CVE-2026-58271

JSON object : View

Products Affected

No product.

CWE

CWE-307

Improper Restriction of Excessive Authentication Attempts

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