CVE-2026-47684: Sync-in Server SSRF Protection Bypass Vulnerability
HIGHCVE-2026-47684 is a HIGH (CVSS 7.7) ssrf protection bypass vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Sync-in Server libraries in the npm ecosystem. The issue involves ssrf protection bypass via ipv4-mapped ipv6 addresses in regexpprivateip. Remediation is available by upgrading affected packages to version 2.3.0.
CVE-2026-47684 at a Glance
Security Impact
CVSS: 7.7
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N).
How to Fix CVE-2026-47684
To remediate this vulnerability, upgrade all affected Sync-in Server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
npm install @sync-in/server@2.3.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls @sync-in/serverHow to Check if You Are Affected
To determine whether your Node.js application is affected by CVE-2026-47684, inspect your project dependencies using npm:
npm ls @sync-in/serverAnalyze the terminal output to locate any version of Sync-in Server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.3.0), your application is affected.
Note: The npm ls @sync-in/server command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-918: Server-Side Request Forgery (SSRF), where the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination. In Sync-in Server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-47684 Affected Sync-in Server Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
@sync-in/server
|
npm |
< 2.3.0
|
2.3.0
|
References
Frequently Asked Questions
What is CVE-2026-47684?
Which Sync-in Server versions are affected?
What version fixes CVE-2026-47684?
Is @sync-in/server affected?
What is the CVSS score of CVE-2026-47684?
What CWE is associated with CVE-2026-47684?
How can I check npm dependencies for CVE-2026-47684?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-q4x5-8cj6-52wg",
"modified" : "2026-07-08T17:36:17Z",
"published" : "2026-06-05T16:34:59Z",
"aliases" : [ "CVE-2026-47684" ],
"summary" : "Sync-in Server: SSRF protection bypass via IPv4-mapped IPv6 addresses in regExpPrivateIP",
"details" : "Summary:\nThe 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.\n\nAffected components\n\nbackend/src/applications/files/services/files-manager.service.ts – downloadFromUrl() checks regExpPrivateIP against request.socket.remoteAddress.\nbackend/src/applications/files/utils/url-file.ts – regExpPrivateIP does not include ::ffff:<ipv4> variants.\n\nDetails:\nThe 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.\n\nPoC:\n[poc.pdf](https://github.com/user-attachments/files/26990874/poc.pdf)\n\n\n\n\nProof:\n<img width=\"1080\" height=\"842\" alt=\"1000226655\" src=\"https://github.com/user-attachments/assets/797cea83-0a08-4a16-a91b-31c51068d473\" />\n\n\n\n\n\nImpact:\nAn 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.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "npm",
"name" : "@sync-in/server"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "2.3.0"
} ]
} ],
"database_specific" : {
"last_known_affected_version_range" : "<= 2.2.1"
}
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/Sync-in/server/security/advisories/GHSA-q4x5-8cj6-52wg"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-47684"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/Sync-in/server"
}, {
"type" : "WEB",
"url" : "https://github.com/Sync-in/server/releases/tag/v2.3.0"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-918" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-06-05T16:34:59Z",
"nvd_published_at" : "2026-06-16T15:16:41Z"
}
}