ssrfcheck is a library that checks if a string contains a potential SSRF attack. In 1.3.0 and earlier, ssrfcheck fails to block Server-Side Request Forgery attacks when the target private IP address is encoded as an IPv4-mapped IPv6 address (e.g. http://[::ffff:127.0.0.1]/). The WHATWG URL parser built into Node.js silently normalizes the IPv4 notation inside the brackets to compressed hex form ([::ffff:7f00:1]) before the library's private-IP regex ever runs. The regex was written to match dot-notation only and therefore never matches any real input — all seven IANA private IPv4 ranges, including the AWS/GCP/Azure metadata address 169.254.169.254, are bypassed. Any application using isSSRFSafeURL() to guard HTTP requests made with user-supplied URLs is fully exposed to SSRF.

Project Subscriptions

Vendors Products
Felipperegazio Subscribe
Ssrf Check Subscribe
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-j4rj-2jr5-m439 ssrfcheck Vulnerable to Server-Side Request Forgery (SSRF) and Incomplete List of Disallowed Inputs
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 13 May 2026 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 13 May 2026 10:00:00 +0000

Type Values Removed Values Added
First Time appeared Felipperegazio
Felipperegazio ssrf Check
Vendors & Products Felipperegazio
Felipperegazio ssrf Check

Tue, 12 May 2026 18:15:00 +0000

Type Values Removed Values Added
Description ssrfcheck is a library that checks if a string contains a potential SSRF attack. In 1.3.0 and earlier, ssrfcheck fails to block Server-Side Request Forgery attacks when the target private IP address is encoded as an IPv4-mapped IPv6 address (e.g. http://[::ffff:127.0.0.1]/). The WHATWG URL parser built into Node.js silently normalizes the IPv4 notation inside the brackets to compressed hex form ([::ffff:7f00:1]) before the library's private-IP regex ever runs. The regex was written to match dot-notation only and therefore never matches any real input — all seven IANA private IPv4 ranges, including the AWS/GCP/Azure metadata address 169.254.169.254, are bypassed. Any application using isSSRFSafeURL() to guard HTTP requests made with user-supplied URLs is fully exposed to SSRF.
Title ssrfcheck: Server-Side Request Forgery (SSRF) and Incomplete List of Disallowed Inputs
Weaknesses CWE-184
CWE-918
References
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N'}


Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-13T14:37:49.368Z

Reserved: 2026-05-04T16:59:09.089Z

Link: CVE-2026-43929

cve-icon Vulnrichment

Updated: 2026-05-13T14:37:03.972Z

cve-icon NVD

Status : Deferred

Published: 2026-05-12T18:17:28.970

Modified: 2026-05-13T18:24:31.310

Link: CVE-2026-43929

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-13T09:45:09Z

Weaknesses