The vulnerability resides in the amf_namf_callback_handle_sdm_data_change_notify function of the Open5GS AMF SBI Endpoint. Manipulating the changeItem.newValue parameter can cause a denial of service to the AMF service. The attack can be started remotely and published exploits exist. The effect is a disruption of the 5G network core component, leading to service unavailability for users relying on that service.

All Open5GS deployments that use the AMF SBI Endpoint and are running version 2.7.7 or earlier are affected. The flaw appears through the /namf-callback/v1/{id}/sdmsubscription-notify endpoint.

The CVSS score is 5.3 indicating a moderate risk. The EPSS score is less than 1% but an exploit has already been published and can be executed remotely. The vulnerability is not listed in the CISA KEV catalog, so there is no official warning yet. Based on the description, it is inferred that an attacker with network access to the AMF endpoint could repeatedly probe the service and trigger a denial of service until the system is patched or protected.