CVE-2026-43929Public exploitNetwork attack vector

SSRF via normalized IPv4-mapped IPv6 addresses

Published May 12, 2026 · Updated May 12, 2026

SSRF in ssrfcheck 1.3.0 and earlier allows remote attackers to reach private network resources via IPv4-mapped IPv6 URLs. Node.js normalizes embedded IPv4 dot notation into compressed hexadecimal form before src/is-private-ip.js applies a dot-only private-address regex, so isSSRFSafeURL() returns safe. Applications are exposed when they use that result to authorize requests from untrusted URLs; the bypass requires no authentication or non-default options and can expose metadata, loopback, or internal services.

CVSS severity8.2
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in ssrfcheck 1.3.0 and earlier allows remote attackers to reach private network resources via IPv4-mapped IPv6 URLs. Node.js normalizes embedded IPv4 dot notation into compressed hexadecimal form before src/is-private-ip.js applies a dot-only private-address regex, so isSSRFSafeURL() returns safe. Applications are exposed when they use that result to authorize requests from untrusted URLs; the bypass requires no authentication or non-default options and can expose metadata, loopback, or internal services.

The record

CVE
CVE-2026-43929
Published
May 12, 2026
Updated
May 12, 2026
Vendor
Felippe Regazio
Product
ssrfcheck
Classifications
CWE-184, CWE-918, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 2026CVE publishedPublication date reported by the CVE source.
  2. May 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=<= 1.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Felippe Regazio · ssrfcheckversion=<= 1.3.0

Published CVSS scores

8.2GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-184Incomplete List of Disallowed Inputs
CWE-918Server-Side Request Forgery (SSRF)
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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