Sync-in Server: SSRF protection bypass via IPv4-mapped IPv6 addresses in regExpPrivateIP
Priority HIGH 67CWE-918Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-918 and the CVSS impact.
Summary
Sync-in Server is a secure, open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.3.0, the private IP blocklist regex used in the URL download feature does not match IPv4-mapped IPv6 addresses (e.g. ::ffff:127.0.0.1), allowing SSRF protection to be bypassed on dual-stack systems. Version 2.3.0 fixes the issue.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00222 12th percentileScored 2026-11-07
Fix Fixed server (Sync-in): 2.3.0@sync-in/server (npm): 2.3.0
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Sync-in | server | before 2.3.0 | 2.3.0 | Patch available | CNA |
| — | @sync-in/server (npm) | before 2.3.0 | 2.3.0 | Patch available | GHSA-q4x5-8cj6-52wg |
- server VendorSync-in Affected before 2.3.0 Fixed in 2.3.0 Patch available CNA
- @sync-in/server (npm) Vendor— Affected before 2.3.0 Fixed in 2.3.0 Patch available GHSA-q4x5-8cj6-52wg
Remediation
- Fix · CNA server (Sync-in) Fixed in 2.3.0
- Fix · GHSA-q4x5-8cj6-52wg @sync-in/server (npm) Fixed in 2.3.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-47684
- 2026-10-03 Alias added: GHSA-q4x5-8cj6-52wg
References
More Sync-in vulnerabilities
- TI-2026-41960 Sync-in Server has a complete 2FA Bypass via `POST /api/auth/token` CVSS 3.1HIGH 8.1
- TI-2026-29787 Username Enumeration via Timing Attack CVSS 4.0MEDIUM 6.9
- TI-2026-41962 @sync-in/server vulnerable to TOTP Brute-Force via `POST /api/app/sync/register` CVSS 3.1MEDIUM 6.8
- TI-2026-41963 Sync-in Server has Username/Login Enumeration via Timing Side-Channel on POST… CVSS 3.1MEDIUM 5.3
- TI-2026-41961 Sync-in Server has a ReDoS via Unsanitized Regex in Sync Diff `pathFilters` CVSS 3.1MEDIUM 6.5
- TI-2025-41214 A Stored Cross-Site Scripting (XSS) vulnerability in Sync-in Server before 1.9.3 allows… CVSS 3.1MEDIUM 6.1
Sources
- CVE-2026-47684 · CVE Program
- CVE-2026-47684 · NVD
- FIRST EPSS
- GHSA-q4x5-8cj6-52wg · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences