CVE-2026-47684: CWE-918: Server-Side Request Forgery (SSRF) in Sync-in server
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.
AI Analysis
Technical Summary
The Sync-in Server before version 2.3.0 has a SSRF vulnerability (CWE-918) in its URL download feature. The private IP blocklist regex used to prevent SSRF does not recognize IPv4-mapped IPv6 addresses (e.g., ::ffff:127.0.0.1), enabling attackers to bypass SSRF protections on systems supporting both IPv4 and IPv6. This vulnerability is addressed in Sync-in Server version 2.3.0.
Potential Impact
An attacker with low privileges can bypass SSRF protections to cause the server to make unauthorized network requests to internal or protected resources. The CVSS score of 7.7 reflects high severity with network attack vector, low attack complexity, requiring low privileges, no user interaction, and potential for high confidentiality impact without affecting integrity or availability.
Mitigation Recommendations
Upgrade Sync-in Server to version 2.3.0 or later, where the private IP blocklist regex correctly handles IPv4-mapped IPv6 addresses, mitigating the SSRF vulnerability. Patch status is not explicitly stated but the vendor fixed the issue in 2.3.0, so applying this official fix is recommended.
CVE-2026-47684: CWE-918: Server-Side Request Forgery (SSRF) in Sync-in server
Description
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.
CVSS v3.1
Score 7.7high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Sync-in Server before version 2.3.0 has a SSRF vulnerability (CWE-918) in its URL download feature. The private IP blocklist regex used to prevent SSRF does not recognize IPv4-mapped IPv6 addresses (e.g., ::ffff:127.0.0.1), enabling attackers to bypass SSRF protections on systems supporting both IPv4 and IPv6. This vulnerability is addressed in Sync-in Server version 2.3.0.
Potential Impact
An attacker with low privileges can bypass SSRF protections to cause the server to make unauthorized network requests to internal or protected resources. The CVSS score of 7.7 reflects high severity with network attack vector, low attack complexity, requiring low privileges, no user interaction, and potential for high confidentiality impact without affecting integrity or availability.
Mitigation Recommendations
Upgrade Sync-in Server to version 2.3.0 or later, where the private IP blocklist regex correctly handles IPv4-mapped IPv6 addresses, mitigating the SSRF vulnerability. Patch status is not explicitly stated but the vendor fixed the issue in 2.3.0, so applying this official fix is recommended.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-19T21:18:20.402Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a31650b0b89be6888c92027
Added to database: 6/16/2026, 3:00:27 PM
Last enriched: 6/16/2026, 3:15:25 PM
Last updated: 6/17/2026, 4:59:03 AM
Views: 12
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