Free5GC up to 1.4.2 PCF SBI Interface router.Use resource consumption

Summaryinfo

A vulnerability, which was classified as problematic, was found in Free5GC up to 1.4.2. Affected by this issue is the function router.Use of the component PCF SBI Interface. Executing a manipulation can lead to resource consumption. This vulnerability is tracked as CVE-2026-41135. The attack can be launched remotely. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Free5GC up to 1.4.2. It has been declared as problematic. This vulnerability affects the function router.Use of the component PCF SBI Interface. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. CVE summarizes:

free5GC UDR is the Policy Control Function (PCF) for free5GC, an an open-source project for 5th generation (5G) mobile core networks. A memory leak vulnerability in versions prior to 1.4.3 allows any unauthenticated attacker with network access to the PCF SBI interface to cause uncontrolled memory growth by sending repeated HTTP requests to the OAM endpoint. The root cause is a `router.Use()` call inside an HTTP handler that registers a new CORS middleware on every incoming request, permanently growing the Gin router's handler chain. This leads to progressive memory exhaustion and eventual Denial of Service of the PCF, preventing all UEs from obtaining AM and SM policies and blocking 5G session establishment. Version 1.4.3 contains a patch.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-41135 since 04/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 1.4.3 eliminates this vulnerability. Applying the patch 599803b1b2eb4611e26d5216481ee142bce71a16 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

• Free5GC

Version

• 1.4.0
• 1.4.1
• 1.4.2

License

• open-source

Website

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

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