free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's UDR nudr-dr DELETE /subscription-data/{ueId}/{servingPlmnId}/ee-subscriptions/{subsId}/amf-subscriptions handler contains a nil-pointer dereference reachable from a single authenticated request, after one preparatory authenticated EE-subscription create. The handler checks _, ok = UESubsData.EeSubscriptionCollection[subsId] and sets a 404 problem-details on the miss path, but then continues to UESubsData.EeSubscriptionCollection[subsId].AmfSubscriptionInfos -- dereferencing the same missing entry instead of returning. Gin recovery converts the panic into HTTP 500, but the endpoint remains repeatedly panicable. This vulnerability is fixed in 4.2.2.
https://github.com/free5gc/udr/pull/60
https://github.com/free5gc/udr/commit/8a1d3c63be99d378806d771f086ff32f1867da99
https://github.com/free5gc/free5gc/security/advisories/GHSA-4rqf-grm6-vf75