Vulnerability 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.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/felippe-regazio/ssrfcheck/security/advisories/GHSA-j4rj-2jr5-
- https://github.com/felippe-regazio/ssrfcheck/security/advisories/GHSA-j4rj-2jr5-
FAQ
What is CVE-2026-43929?
CVE-2026-43929 is a vulnerability with a CVSS score of 8.2 (HIGH). 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 i...
How severe is CVE-2026-43929?
CVE-2026-43929 has been rated HIGH with a CVSS base score of 8.2/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-43929?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.