A remote attacker can induce a buffer overflow in the Open5GS NAS 5GS decoder chain by sending a NAS PDU with a mutated message type byte, causing the open‑source 5G core component to crash and result in a denial of service. The flaw stems from lack of bounds checking when parsing the message type, enabling the attacker to corrupt local memory.

The vulnerability has been confirmed in Open5GS version 2.7.0, the open‑source 5G core network stack. No other major versions have been documented in the advisory, so systems running 2.7.0 or older are assumed to be at risk.

Because the exploit is carried out by crafting a malformed NAS PDU over the network, it is remotely accessible to anyone with routing or physical access to the Open5GS server. The EPSS score of <1% and the fact that the vulnerability is not listed in CISA KEV mitigate the perceived exploitation probability, but the CVSS score of 7.5 demonstrates a moderate severity and the ability to crash a core network component warrants a high availability risk assessment. No patch is referenced in the advisory, so the vulnerability remains unfixed in the listed version.