free5GC up to 1.4.4 AUSF net/url.Parse supiOrSuci input validation

Summaryinfo

A vulnerability described as critical has been identified in free5GC up to 1.4.4. The affected element is the function net/url.Parse of the component AUSF. Executing a manipulation of the argument supiOrSuci can lead to input validation. This vulnerability appears as CVE-2026-53551. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability classified as critical was found in free5GC up to 1.4.4. This vulnerability affects the function net/url.Parse of the component AUSF. The manipulation of the argument supiOrSuci with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

free5GC is an open-source implementation of the 5G core network. Prior to 1.4.5, the free5GC AUSF (Authentication Server Function) does not validate the supiOrSuci field in UE authentication requests. Null bytes (\x00) and other control characters pass through JSON parsing unchanged and are forwarded to the UDM in an unescaped URL path. This causes Go's net/url.Parse() to fail, returning HTTP 500 "System failure" and leaking internal stack traces. An unauthenticated attacker can trigger this at scale causing denial of service for all subscribers attempting authentication through the affected AUSF. This vulnerability is fixed in 1.4.5.

The advisory is available at github.com. This vulnerability was named CVE-2026-53551 since 06/09/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 1.4.5 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-51628). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Name

• free5GC

Version

• 1.4.0
• 1.4.1
• 1.4.2
• 1.4.3
• 1.4.4

Website

• Product: https://github.com/free5gc/free5gc/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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