CVE-2026-44328: free5GC: SMF UPI DELETE /upi/v1/upNodesLinks/{ref} panics on AN-node deletion via nil UPF dereference; unauthenticated, state-mutating

Vulnerability summary

CVE-2026-44328 is a high (CVSS 8.2) vulnerability in free5gc. EPSS estimates a 0.54% chance of exploitation in the next 30 days, higher than 44.5% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 27-05-2026
   PublishedVulnerability first disclosed.
2. 27-05-2026
   Last modifiedVulnerability information updated.

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.

• CWE-306Missing Authentication for Critical FunctionThe product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
• CWE-476NULL Pointer DereferenceThe product dereferences a pointer that it expects to be valid but is NULL.
• CWE-862Missing AuthorizationThe product does not perform an authorization check when an actor attempts to access a resource or perform an action.