Free5GC up to 4.2.1 subscriptions RLock race condition

Summaryinfo

A vulnerability was found in Free5GC up to 4.2.1 and classified as problematic. Affected is the function RLock of the file /nbsf-management/v1/subscriptions/. Such manipulation leads to race condition. This vulnerability is listed as CVE-2026-44318. The attack may be performed from remote. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Free5GC up to 4.2.1. It has been rated as problematic. Affected by this issue is the function RLock of the file /nbsf-management/v1/subscriptions/. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. Impacted is availability. CVE summarizes:

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's BSF PUT /nbsf-management/v1/subscriptions/{subId} handler has an unsynchronized write on the global Subscriptions map. The handler first reads the map under RLock() via BSFContext.GetSubscription(subId), but if the subscription does not exist, ReplaceIndividualSubcription() writes back to the same map directly without taking the mutex (bsfContext.BsfSelf.Subscriptions[subId] = subscription). Under concurrent authenticated PUT load, one goroutine can read while another writes the map, which causes the Go runtime to abort the process with fatal error: concurrent map read and map write (Go runtime panics that come from concurrent map access bypass recover() and terminate the process). The BSF container exits with code 2 -- the entire BSF SBI surface goes down until restart. This vulnerability is fixed in 4.2.2.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-44318 since 05/05/2026. The exploitation is known to be easy. The attack may be launched remotely. Technical details are known, but there is no available exploit.

Upgrading to version 4.2.2 eliminates this vulnerability.

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Productinfo

Name

• Free5GC

Version

• 4.2.0
• 4.2.1

Website

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

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