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.
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Affected Vendors & Products
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History
Wed, 13 May 2026 15:15:00 +0000
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ssvc
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Wed, 13 May 2026 10:00:00 +0000
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Felipperegazio
Felipperegazio ssrf Check |
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| Vendors & Products |
Felipperegazio
Felipperegazio ssrf Check |
Tue, 12 May 2026 18:15:00 +0000
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| 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 |
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| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-05-12T17:49:12.192Z
Updated: 2026-05-13T14:37:49.368Z
Reserved: 2026-05-04T16:59:09.089Z
Link: CVE-2026-43929
Updated: 2026-05-13T14:37:03.972Z
Status : Received
Published: 2026-05-12T18:17:28.970
Modified: 2026-05-12T18:17:28.970
Link: CVE-2026-43929
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