CVE-2026-42081
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.27%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.1 HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- EPSS
- 0.27% probability · 19th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-358
- Affected
- free5gc/free5gc
- Source
- security-advisories@github.com
References
- https://github.com/free5gc/free5gc/security/advisories/GHSA-77x9-rf64-92gvExploit, Vendor Advisory
- https://github.com/free5gc/free5gc/security/advisories/GHSA-77x9-rf64-92gvExploit, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.