CVE-2026-42081Public exploit

Handover denial via unchecked capability overwrite

Published May 27, 2026 · Updated May 27, 2026

Improper security checking in free5GC before 4.2.2 allows attackers controlling a gNB to persistently interrupt UE handovers. The AMF handlePathSwitchRequestMain function overwrites locally stored UE Security Capabilities with PathSwitchRequest values without verifying a match. Control of a connected gNB is required; poisoned capability state propagates to later handover messages and causes handovers to fail until UE re-registration.

CVSS severity6.1
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper security checking in free5GC before 4.2.2 allows attackers controlling a gNB to persistently interrupt UE handovers. The AMF handlePathSwitchRequestMain function overwrites locally stored UE Security Capabilities with PathSwitchRequest values without verifying a match. Control of a connected gNB is required; poisoned capability state propagates to later handover messages and causes handovers to fail until UE re-registration.

The record

CVE
CVE-2026-42081
Published
May 27, 2026
Updated
May 27, 2026
Vendor
free5GC
Product
free5GC
Classifications
CWE-358, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.2.2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

free5GC · free5GCversion=< 4.2.2

Published CVSS scores

7.1NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
6.1GitHub, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-358Improperly Implemented Security Check for Standard
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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