free5GC: UE Security Capability bypass on NGAP PathSwitchRequest

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, the AMF in Free5GC does not verify the UE Security Capabilities received in NGAP PathSwitchRequest messages against its locally stored values, as mandated by 3GPP TS 33.501 §6.7.3.1. A malicious gNB can overwrite the AMF's stored UE security capabilities with arbitrary values, which are then propagated in PathSwitchRequest Acknowledge messages and subsequent Handover Request messages. This leads to persistent handover denial-of-service for affected UEs. This vulnerability is fixed in 4.2.2.

Source published

27 May 2026 15:59:58 UTC

Source modified

27 May 2026 17:56:05 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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CVSS 3.1 · 6.1 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:L