CVE-2023-37023

CVE-2023-37023 is a reachable assertion vulnerability (CWE-617) affecting Open5GS Mobility Management Entity (MME) versions up to and including 2.6.4. The issue resides in the Uplink NAS Transport packet handler, where a packet missing its MME_UE_S1AP_ID field triggers an assertion failure, causing the Open5GS MME to crash. This flaw was published on 2025-01-22 and carries a CVSS v3.1 base score of 8.6 (AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H), indicating high severity due to its potential for significant availability disruption.

Any unauthenticated attacker with network access to the affected Open5GS MME can exploit this vulnerability by sending specially crafted Uplink NAS Transport packets lacking the required MME_UE_S1AP_ID field. A single such packet crashes the service, and repeated transmissions enable a denial-of-service condition, rendering the MME unavailable. The attack requires low complexity, no user interaction, and exploits a scope change to amplify impact across the system.

Mitigation details and patches are outlined in the advisory available at https://cellularsecurity.org/ransacked. Security practitioners should consult this reference for upgrade guidance to versions beyond 2.6.4 and any interim workarounds.