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Vulnerabilities

Vulnerability · CVE-2026-43929

ssrfcheck is a library that checks if a string contains a potential SSRF attack.

Published May 12, 2026 · catalog updated Jun 17, 2026 · ssrfcheck is a library

Check if you run it

No confirmed exploitation is on record for CVE-2026-43929. EPSS is 0.36%. Act only if a listed version of ssrfcheck is a library is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (ssrfcheck is a library).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.2
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.36%
Remediation
Version ranges on file
Affected products
stated named in the record

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • stated named in the record<= 1.3.0

How to fix CVE-2026-43929

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-43929. EPSS is 0.36%. Act only if a listed version of ssrfcheck is a library is installed.

Which versions are affected?

Compare what you have installed with named in the record <= 1.3.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-184; CWE-918: Server-Side Request Forgery (SSRF). EPSS 0.36%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 12, 2026 · NIST NVD

    Detected

    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 ([

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 ([

Sources

  • CVE.orgVulnerability recordCVE-2026-43929

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-43929

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-43929

    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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.