Executive brief
Open5GS is an open-source implementation of 5G Core and EPC mobile network functions. A vulnerability in how the Access and Mobility Management Function (AMF) handles mobile identity information allows an unauthenticated attacker to crash the core network service. This results in a total denial of service for all mobile subscribers and connected radio base stations served by the affected component.
Technical details
A heap out-of-bounds read exists in the `ogs_nas_5gs_decode_5gs_mobile_identity()` function within `lib/nas/5gs/ies.c`. The root cause is a failure to validate that the attacker-declared length of a mobile identity (GUTI or 5G-S-TMSI) is sufficient for the identity type specified. When the AMF processes a NAS Registration, Deregistration, or Service Request, it aliases a pointer into the packet buffer without a minimum-length check and subsequently casts it to a fixed-size struct. An attacker using a rogue base station (gNB) can send a malformed NAS message before authentication occurs, causing the AMF to read past the buffer boundary. In hardened or ASAN-enabled builds, this results in an immediate crash of the AMF process, dropping all active subscriber sessions.
Affected products
- Open5GS Open5GS <= 2.7.7
Timeline
- 2026-06-05: advisory: Vendor advisory published on GitHub
- 2026-07-14: disclosed: CVE published to NVD