CVE-2026-44327
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.31%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 10.0 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H
- EPSS
- 0.31% probability · 24th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-306, CWE-862
- Affected
- free5gc/free5gc
- Source
- security-advisories@github.com
References
- https://github.com/free5gc/free5gc/issues/861Exploit, Issue Tracking
- https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3Exploit, Vendor Advisory
- https://github.com/free5gc/nef/pull/23Issue Tracking, Patch
- https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3Exploit, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.