CVE-2026-47684

Summary:
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.

Affected components

backend/src/applications/files/services/files-manager.service.ts, downloadFromUrl() checks regExpPrivateIP against request.socket.remoteAddress.
backend/src/applications/files/utils/url-file.ts, regExpPrivateIP does not include ::ffff: variants.

Details:
The regExpPrivateIP regex in backend/src/applications/files/utils/url-file.ts correctly blocks standard IPv4 private ranges but does not include ::ffff: prefixed variants. On dual-stack systems, Node.js can report a socket's remoteAddress in IPv4-mapped IPv6 form, meaning the check in FilesManager.downloadFromUrl() can be bypassed entirely.

PoC:
poc.pdf

Proof:

Impact:
An attacker can supply a crafted URL pointing to an internal address that gets reported as ::ffff:127.0.0.1 or ::ffff:10.x.x.x, causing the server to fetch internal resources that should be blocked. Any user with access to the file download feature is a potential attacker.

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

CVE-2026-47684 has a CVSS score of 7.7 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.3.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-47684? CVE-2026-47684 is a high-severity server-side request forgery (SSRF) vulnerability in @sync-in/server (npm), affecting versions <= 2.2.1. It is fixed in 2.3.0. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. How severe is CVE-2026-47684? CVE-2026-47684 has a CVSS score of 7.7 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @sync-in/server are affected by CVE-2026-47684? @sync-in/server (npm) versions <= 2.2.1 is affected.
4. Is there a fix for CVE-2026-47684? Yes. CVE-2026-47684 is fixed in 2.3.0. Upgrade to this version or later.
5. Is CVE-2026-47684 exploitable, and should I be worried? Whether CVE-2026-47684 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-47684 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-47684? Upgrade @sync-in/server to 2.3.0 or later.