{"cve":"CVE-2026-58271","nvd":{"published":"2026-09-21T20:17:26.993","modified":"2026-09-24T23:17:12.723","status":"Deferred","description":"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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","score":6.8},"cwes":["CWE-307"],"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"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:55:23.253742848+00:00"},"epss":{"cve":"CVE-2026-58271","score":0.00219,"percentile":0.12449,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-274f-6w77-8qm9","url":"https://osv.dev/vulnerability/GHSA-274f-6w77-8qm9","summary":"@sync-in/server vulnerable to TOTP Brute-Force via `POST /api/app/sync/register`","modified":"2026-09-22T15:00:47.447960175Z","packages":[{"ecosystem":"npm","name":"@sync-in/server","purl":"pkg:npm/%40sync-in/server","ranges":["<2.4.0"],"fixed":["2.4.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}