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Server-Side Request Forgery (SSRF)Weakness · CWE-918

CVE-2026-47684

HIGH · 7.7 CVSS v3.1 Published 2026-06-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
83/100
Remediation priority · High
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The SSRF protection in Sync-in Server's URL download feature uses a regex blocklist for private IP addresses, but this blocklist only matches traditional IPv4 addresses and fails to match IPv4-mapped IPv6 addresses (e.g., ::ffff:127.0.0.1). On dual-stack systems supporting both IPv4 and IPv6, attackers can bypass the SSRF protection by using the IPv6 representation of private/internal IP addresses.

MitigationUpgrade to Sync-in Server version 2.3.0 or later, which includes the corrected regex to properly block IPv4-mapped IPv6 addresses.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Sync-in Server version
    Locate the installed Sync-in Server version via its administrative UI, version file, or package manager (e.g., rpm -q sync-in-server, dpkg -l sync-in-server, or check /opt/sync-in-server/version 2>/dev/null if standard paths apply)
    Affected if version is below 2.3.0 and the URL download feature is in use
  2. Confirm URL download feature is enabled
    Inspect Sync-in Server configuration files or UI settings for the URL download/integration feature (commonly found under Server Settings, Integrations, or Network settings in the admin panel)
    Affected if URL download functionality is enabled and accessible to users
  3. Verify dual-stack network support
    Check if the host system supports both IPv4 and IPv6 by running 'ip addr show' or 'ipconfig /all' and looking for both inet (IPv4) and inet6 (IPv6) addresses assigned to network interfaces
    Affected if system has active IPv6 connectivity alongside IPv4 (dual-stack configuration)
  4. Test SSRF protection against IPv4-mapped IPv6 address
    If you have access to test the URL download feature, attempt a request to http://[::ffff:127.0.0.1] or http://[::ffff:192.168.1.1] and observe whether the connection is blocked or allowed
    Affected if the SSRF protection allows connections to IPv4-mapped IPv6 representations of private IP addresses (connection succeeds when it should fail)

You are affected if running Sync-in Server version below 2.3.0 with the URL download feature enabled on a dual-stack (IPv4+IPv6) system where the SSRF blocklist does not reject IPv4-mapped IPv6 addresses like ::ffff:127.0.0.1.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Sync-in Server version 2.3.0 or later, which includes the corrected regex to properly block IPv4-mapped IPv6 addresses.

Recommended fix High confidence

2.3.0

  1. 1. Backup the current Sync-in Server installation and all data
  2. 2. Obtain version 2.3.0 from the official Sync-in Server repository or release channel
  3. 3. Stop the running Sync-in Server service
  4. 4. Upgrade or reinstall Sync-in Server to version 2.3.0 following standard upgrade procedures
  5. 5. Restart the Sync-in Server service
  6. 6. Verify the SSRF protection now correctly blocks IPv4-mapped IPv6 addresses (e.g., ::ffff:127.0.0.1)
Caveat Review release notes for version 2.3.0 to check for any breaking changes or migration requirements

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,210
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-47684 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data