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Fencer Vulns
high 7.5

CVE-2026-44321 json

free5GC: SMF UPI POST /upi/v1/upNodesLinks exits the SMF process on overlapping UE pools (unauthenticated, reachable Fatalf)

published 2026-05-08 6 mo ago modified 2026-10-14 25 d ago also EUVD-2026-32577 , GHSA-44qj-cghf-9p97 , GO-2026-5109

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware. The POST /upi/v1/upNodesLinks create-or-update handler accepts attacker-controlled JSON and passes it directly into UpNodesFromConfiguration(), which calls logger.InitLog.Fatalf(...) on several validation failures. One confirmed path is the UE-IP-pool overlap check: a single unauthenticated POST that adds a new UPF whose pool overlaps an existing UPF terminates the entire SMF process (docker ps shows Exited (1)), not just the goroutine. 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

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.36% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/free5gc/free5gc/security/advisories/GHSA-44qj-cghf-9p97 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/free5gc/free5gc/issues/906 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

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

Affected products

  • free5gc free5gc

Classification

Weakness
  • CWE-306 Missing Authentication for Critical Functionality
  • CWE-617 Reachable Assertion
  • CWE-862 Missing Authorization

References

Sources

Fencer Vulns 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.