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Vulnerability record · CVE-2026-44321 · published 27 May 2026

CVE-2026-44321: Free5gc missing authentication for critical function vulnerability

Free5gc · Free5gc

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.

7.5 CVSS 3.1 High EPSS 0.61% · top 53.2% CWE-306 · Missing authentication for critical functionCWE-617 · CWE-617
7.5CVSS 3.1 base score
0.61%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References, 3 tagged exploit
17 Jun 2026Last modified by NVD

Description

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/free5gc/free5gc/issues/906 ExploitIssue Tracking
https://github.com/free5gc/free5gc/security/advisories/GHSA-44qj-cghf-9p97 ExploitVendor Advisory
https://github.com/free5gc/smf/commit/e0974e07ddab44a67d36a563cca383b2449e33e5 Patch
https://github.com/free5gc/smf/pull/203 Issue TrackingPatch
https://github.com/free5gc/free5gc/security/advisories/GHSA-44qj-cghf-9p97 ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-44321), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.