Auth bypass in Free5gc
CVE-2026-44329
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 OAuth2/bearer-token authorization middleware. A network attacker who can reach SMF on the SBI can hit UPI endpoints with no Authorization header at all, and the requests reach the SMF business handlers. In the running Docker lab this was directly demonstrated for read (GET /upi/v1/upNodesLinks), write (POST /upi/v1/upNodesLinks with attacker-controlled UP-node and link payload), and delete (DELETE /upi/v1/upNodesLinks/{nodeID}) operations. This vulnerability is fixed in 4.2.2.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H.
EPSS exploit prediction
EPSS: 0.006 (44.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 45th percentile — 44.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.006 · change: +0.002
Affected products
- Free5gc — versions < 4.2.2
Weakness classification (CWE)
References
- github.com/free5gc/free5gc/security/advisories/GHSA-3258-qmv8-frp3 (Exploit, Vendor Advisory)
- github.com/free5gc/free5gc/issues/887 (Exploit, Issue Tracking)
- github.com/free5gc/smf/pull/197 (Patch, Issue Tracking)
- github.com/free5gc/smf/commit/e23ce97565f285eb99eed153743c62bf4c767c6e (Patch)
Frequently asked questions
- What is CVE-2026-44329?
- CVE-2026-44329 is a critical-severity vulnerability in Free5gc, classified under Missing Authentication for Critical Function. CVSS score: 10.0/10. Published 2026-05-27.
- How severe is CVE-2026-44329?
- Critical severity. CVSS v3 base score is 10.0 out of 10.