Auth bypass in Free5gc
CVE-2026-44328
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. On top of that, the DELETE /upi/v1/upNodesLinks/{upNodeRef} handler unconditionally dereferences upNode.UPF after the type-guarded async release, even though AN-typed nodes are constructed without a UPF object. As a result, a single unauthenticated DELETE /upi/v1/upNodesLinks/gNB1 request crashes the handler with a nil-pointer panic AND mutates the in-memory user-plane topology before panicking (the UpNodeDelete(upNodeRef) line runs first). This is an unauthenticated, state-mutating panic-DoS sink that an off-path network attacker can trigger by name against any AN entry. This vulnerability is fixed in 4.2.2.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H.
EPSS exploit prediction
EPSS: 0.005 (43.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 43.1% 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: 0.005 · change: +0.002
Affected products
- Free5gc — versions < 4.2.2
Weakness classification (CWE)
References
- github.com/free5gc/free5gc/security/advisories/GHSA-p9mg-74mg-cwwr (Exploit, Vendor Advisory)
- github.com/free5gc/free5gc/issues/905 (Exploit, Issue Tracking)
- github.com/free5gc/smf/pull/199 (Patch, Issue Tracking)
- github.com/free5gc/smf/commit/b57bc48081c3d3a2f333d02eb78e4fd31a120deb (Patch)
Frequently asked questions
- What is CVE-2026-44328?
- CVE-2026-44328 is a high-severity vulnerability in Free5gc, classified under Missing Authentication for Critical Function. CVSS score: 8.2/10. Published 2026-05-27.
- How severe is CVE-2026-44328?
- High severity. CVSS v3 base score is 8.2 out of 10.