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CVE-2026-42081

HIGHCVSS 7.1/10EPSS 0.27%

Last modified

CVE-2026-42081 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 0.27% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.1/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS Probability
0.27%

18.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
Free5gcFree5gc< 4.2.2

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-42081?
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.
How severe is CVE-2026-42081?
CVE-2026-42081 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.
How do I fix CVE-2026-42081?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-42081?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST