CVE-2026-44328 free5GC's SMF UPI DELETE /upi/v1/upNodesLinks/{ref} panics on AN-node deletion via nil UPF dereference; unauthenticated, state-mutating
Unauthenticated attackers can crash the SMF and corrupt user-plane topology via a nil-pointer dereference in the UPI management API.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-44328?
CVE-2026-44328 is a high-severity vulnerability in Free5gc Free5gc, published on 27 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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. 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.
Which versions are affected by CVE-2026-44328?
3 open source packages ship an affected version, including github.com/free5gc/smf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/free5gc/smf Go | All versions | 1.4.3 |
github.com/free5gc/smf Go | All versions | 1.4.3 |
github.com/free5gc/smf Go | All versions | 1.4.3 |
Products include Free5gc Free5gc.
How do I fix CVE-2026-44328?
Upgrade github.com/free5gc/smf to 1.4.3 or later.
Is CVE-2026-44328 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44328 exists.
Other vulnerabilities in Free5gc Free5gc
- CVE-2026-44327 free5GC: NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler
- CVE-2026-44329 free5GC's SMF UPI management interface lacks auth middleware; unauthenticated topology read/write requests reach handlers
- CVE-2026-44330 free5GC's NEF nnef-pfdmanagement API is unauthenticated; forged bearer tokens can read PFD data and create/delete PFD subscriptions
- CVE-2025-63679 Memory corruption in n/a
- CVE-2026-44315 free5GC's NEF 3gpp-pfd-management API is unauthenticated; forged bearer tokens can create, read, and delete PFD transactions
Sources
Also known as GHSA-p9mg-74mg-cwwr, GO-2026-5537.