CVE-2026-43929: SSRF (CVSS 8.2)

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.

Is your site exposed to CVE-2026-43929?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

8.2

HIGH

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

EPSS — Exploit Prediction

0.0005

Probability of exploitation

0.16%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-184 CWE-184

CWE-918 Server-Side Request Forgery (SSRF)

References

Other References

https://github.com/felippe-regazio/ssrfcheck/security/advisories/GHSA-j4rj-2jr5-m439 https://github.com/felippe-regazio/ssrfcheck/security/advisories/GHSA-j4rj-2jr5-m439

Frequently Asked Questions

What is CVE-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 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. It has a CVSS v3.1 base score of 8.2 (HIGH).

How severe is CVE-2026-43929? +

CVE-2026-43929 has a CVSS v3.1 score of 8.2 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0005, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-43929? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-54090

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Prior …

CVE-2026-61851

Chartbrew is an open-source web application that can connect directly to databases and APIs and use the data to create …

CVE-2025-71355

Picklescan before 0.0.25 fails to detect unsafe global functions in the Numpy library, allowing attackers to bypass static analysis and …

CVE-2026-70470

Flowise is a drag & drop user interface to build a customized large language model flow. Prior to 3.1.3, Flowise …

CVE-2026-93598

ArcadeDB (Maven artifact com.arcadedb:arcadedb-engine) through 26.8.1 contains an incomplete deny-list in the polyglot script sandbox: com.arcadedb.query.polyglot.HostClassLookupFilter.DENIED lists java.util.ResourceBundle as a …

CVE-2026-69263

Flowise is a drag & drop user interface to build a customized large language model flow. Prior to 3.1.3, the …

CVE-2026-43929