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Fencer Intel
medium 6.1

CVE-2026-42081 json

free5GC: UE Security Capability bypass on NGAP PathSwitchRequest

published 6mo ago modified 26d ago also EUVD-2026-32557 , GHSA-77x9-rf64-92gv , GO-2026-5209

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 18%
public exploits
0
none known

Summary

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.

Patch / fix

  • free5gc free5gc 4.2.2
  • free5gc smf 4.2.2
  • free5gc upf 4.2.2
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

Is CVE-2026-42081 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
5mo ago

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/free5gc/free5gc/security/advisories/GHSA-77x9-rf64-92gv referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.1 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:L
GitHub 3.1 6.1 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:L
NVD 3.1 7.1 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected packages

ecosystem package affected fixed in
go github.com/free5gc/amf
<=1.4.3
all versions
 no fix listed

Affected products

  • free5gc free5gc

Classification

Weakness
  • CWE-358 Improperly Implemented Security Check for Standard

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.