Vulnerability · Published May 27, 2026 · Assigned by GitHub_M

CVE-2026-44321free5GC: SMF UPI POST /upi/v1/upNodesLinks exits the SMF process on overlapping UE pools (unauthenticated, reachable Fatalf)

High 7.5

In plain English

A high-severity missing authentication in free5gc from free5gc. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.4%top 69.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/free5gc/smf	no fix listed	GHSA-44qj-cghf-9p97
Go	github.com/free5gc/smf	no fix listed	GO-2026-5109

Affected products (as reported)

Vendor	Product	Versions
free5gc	free5gc	< 4.2.2

Weakness: CWE-306, CWE-617, CWE-862 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

https://github.com/free5gc/free5gc/security/advisories/GHSA-44qj-cghf-9p97 x_refsource_CONFIRM
https://github.com/free5gc/free5gc/issues/906 x_refsource_MISC
https://github.com/free5gc/smf/pull/203 x_refsource_MISC
https://github.com/free5gc/smf/commit/e0974e07ddab44a67d36a563cca383b2449e33e5 x_refsource_MISC