Vulnerability in Sync-In Server
CVE-2026-58270
Sync-in Server is an open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.4.0, the sync diff endpoint compiles a user-supplied string into a `RegExp` with no complexity validation. A catastrophic-backtracking pattern (e.g. `^(a+)+b`) blocks the Node.js event loop, making the entire server unresponsive to all users until the container is restarted. Version 2.4.0 patches the issue.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Sync-in Server — versions < 2.4.0
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
Frequently asked questions
- What is CVE-2026-58270?
- CVE-2026-58270 is a medium-severity vulnerability in Sync-In Server, classified under Inefficient Regular Expression Complexity. CVSS score: 6.5/10. Published 2026-09-21.
- How severe is CVE-2026-58270?
- Medium severity. CVSS v3 base score is 6.5 out of 10.