Vulnerability · Published May 27, 2026 · Assigned by GitHub_M

CVE-2026-44327free5GC: NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler

Critical 10.0

In plain English

A critical-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 0.3% (higher than 24% of all known vulnerabilities).

Severity (CVSS 3.1)10.0Critical

Exploit odds (30 days)0.3%top 75.9% 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 NEF mounts the nnef-oam route group without inbound OAuth2/bearer-token authorization. A network attacker who can reach NEF on the SBI can hit the OAM route with no Authorization header at all and the handler returns 200 OK. The current OAM handler is a stub that returns null, but the structural defect is route-group-scoped: the entire OAM route group has no inbound auth middleware, so every future OAM operation added to this group inherits the missing auth boundary by default. This vulnerability is fixed in 4.2.2.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/free5gc/nef	no fix listed	GHSA-cmpj-2x3g-m7g3
Go	github.com/free5gc/nef	no fix listed	GO-2026-5326

Affected products (as reported)

Vendor	Product	Versions
free5gc	free5gc	< 4.2.2

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

References

https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3 x_refsource_CONFIRM
https://github.com/free5gc/free5gc/issues/861 x_refsource_MISC
https://github.com/free5gc/nef/pull/23 x_refsource_MISC