Vulnerability-Lookup

CVE-2026-40249 (GCVE-0-2026-40249)

Vulnerability from cvelistv5 – Published: 2026-04-16 21:59 – Updated: 2026-04-18 02:47

Title

free5gc UDR fail-open request handling in PolicyDataSubsToNotifySubsIdPut may allow unintended subscription updates after input errors

Summary

free5GC is an open-source implementation of the 5G core network. In versions 4.2.1 and below of the UDR service, the PUT handler for updating Policy Data notification subscriptions at /nudr-dr/v2/policy-data/subs-to-notify/{subsId} does not return after request body retrieval or deserialization errors. Although HTTP 500 or 400 error responses are sent, execution continues and the processor is invoked with a potentially uninitialized or partially initialized PolicyDataSubscription object. This fail-open behavior may allow unintended modification of existing Policy Data notification subscriptions with invalid or empty input, depending on downstream processor and storage behavior. A patched version was not available at the time of publication.

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: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-18 02:47 UTC

CWE

CWE-754 - Improper Check for Unusual or Exceptional Conditions
CWE-636 - Not Failing Securely ('Failing Open')

Assigner

GitHub_M mitre root Scorecard

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: <= 4.2.1	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-40249

Vulnerability from fkie_nvd - Published: 2026-04-16 22:16 - Updated: 2026-06-17 10:44

Severity

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

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/free5gc/free5gc/security/advisories/GHSA-gx38-8h33-pmxr	Exploit, Mitigation, Third Party Advisory

Impacted products

	Vendor	Product	Version
	free5gc	free5gc	*

JSON

To clipboard

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    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Mitigation",
        "Third Party Advisory"
      ],
      "url": "https://github.com/free5gc/free5gc/security/advisories/GHSA-gx38-8h33-pmxr"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-636"
        },
        {
          "lang": "en",
          "value": "CWE-754"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-GX38-8H33-PMXR

Vulnerability from github – Published: 2026-04-14 20:00 – Updated: 2026-04-24 20:35

Summary

free5gc UDR fail-open request handling in PolicyDataSubsToNotifySubsIdPut may allow unintended subscription updates after input errors

Details

Summary

A fail-open request handling flaw in the UDR service causes the /nudr-dr/v2/policy-data/subs-to-notify/{subsId} PUT handler to continue processing requests even after request body retrieval or deserialization errors.

This may allow unintended modification of existing Policy Data notification subscriptions with invalid, empty, or partially processed input, depending on downstream processor behavior.

Details

The endpoint PUT /nudr-dr/v2/policy-data/subs-to-notify/{subsId} is intended to update an existing Policy Data notification subscription only after the HTTP request body has been successfully read and parsed into a valid PolicyDataSubscription object. [file:93]

In the free5GC UDR implementation, the function HandlePolicyDataSubsToNotifySubsIdPut inNFs/udr/internal/sbi/api_datarepository.go does not terminate execution after input-processing failures. [file:93]

The request flow is:

The handler calls c.GetRawData() to read the HTTP request body. [file:93]
If GetRawData() fails, the handler sends an HTTP 500 error response, but does not return. [file:93]
The handler then calls openapi.Deserialize(policyDataSubscription, reqBody, "application/json"). [file:93]
If deserialization fails, the handler sends an HTTP 400 error response, but again does not return. [file:93]
Execution continues and the handler still invokes s.Processor().PolicyDataSubsToNotifySubsIdPutProcedure(c, subsId, policyDataSubscription). [file:93]

As a result, the endpoint operates in a fail-open manner: request processing may continue after fatal input validation or body handling errors, instead of being safely aborted. [file:93]

The issue is compounded by the handler's deserialization call, which passes policyDataSubscription directly to openapi.Deserialize(...) instead of passing a pointer to the destination object. This inconsistent usage further increases the risk that request processing continues with an empty, partially initialized, or otherwise unintended subscription object. [file:93]

This differs from safer handlers in the same file, which use a helper pattern that explicitly returns on body read or deserialization failure before calling the corresponding processor routine. [file:93]

Security Impact

This issue affects a write-capable API that updates Policy Data notification subscriptions identified by subsId. [file:93]
Because execution continues after body read or parsing failure, the processor may receive an uninitialized, partially initialized, or otherwise unintended PolicyDataSubscription object for persistence. [file:93]

The exact runtime impact depends on downstream processor behavior and storage validation. [file:93]
At minimum, this is a security-relevant robustness flaw that can lead to inconsistent request handling or unintended modification attempts; under certain runtime conditions it may allow updates that should not be processed after an input error. [file:93]

Reproduction Status

The code path has been statically confirmed. [file:93] A complete runtime proof of unintended subscription modification after GetRawData() or deserialization failure has not yet been established. [file:93]

Patch

The handler should immediately terminate after sending an error response for body read or deserialization failure. [file:93]

A minimal fix is to add missing return statements in HandlePolicyDataSubsToNotifySubsIdPut and pass a pointer to the destination object during deserialization: [file:93]

reqBody, err := c.GetRawData()
if err != nil {
    logger.DataRepoLog.Errorf("Get Request Body error: %+v", err)
    pd := openapi.ProblemDetailsSystemFailure(err.Error())
    c.Set(sbi.IN_PB_DETAILS_CTX_STR, pd.Cause)
    c.JSON(http.StatusInternalServerError, pd)
    return
}

err = openapi.Deserialize(&policyDataSubscription, reqBody, "application/json")
if err != nil {
    logger.DataRepoLog.Errorf("Deserialize Request Body error: %+v", err)
    pd := util.ProblemDetailsMalformedReqSyntax(err.Error())
    c.Set(sbi.IN_PB_DETAILS_CTX_STR, pd.Cause)
    c.JSON(http.StatusBadRequest, pd)
    return
}

Severity

5.3 (Medium)


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

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

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/free5gc/udr"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "1.4.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40249"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-636",
      "CWE-754"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-14T20:00:59Z",
    "nvd_published_at": "2026-04-16T22:16:38Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\nA fail-open request handling flaw in the UDR service causes the `/nudr-dr/v2/policy-data/subs-to-notify/{subsId}` PUT handler to continue processing requests even after request body retrieval or deserialization errors.\n\nThis may allow unintended modification of existing Policy Data notification subscriptions with invalid, empty, or partially processed input, depending on downstream processor behavior.\n\n### Details\nThe endpoint `PUT /nudr-dr/v2/policy-data/subs-to-notify/{subsId}` is intended to update an existing Policy Data notification subscription only after the HTTP request body has been successfully read and parsed into a valid `PolicyDataSubscription` object. [file:93]\n\nIn the free5GC UDR implementation, the function `HandlePolicyDataSubsToNotifySubsIdPut` in`NFs/udr/internal/sbi/api_datarepository.go` does not terminate execution after input-processing failures. [file:93]\n\nThe request flow is:\n\n1. The handler calls `c.GetRawData()` to read the HTTP request body. [file:93]\n2. If `GetRawData()` fails, the handler sends an HTTP 500 error response, but **does not return**. [file:93]\n3. The handler then calls `openapi.Deserialize(policyDataSubscription, reqBody, \"application/json\")`. [file:93]\n4. If deserialization fails, the handler sends an HTTP 400 error response, but again **does not return**. [file:93]\n5. Execution continues and the handler still invokes `s.Processor().PolicyDataSubsToNotifySubsIdPutProcedure(c, subsId, policyDataSubscription)`. [file:93]\n\nAs a result, the endpoint operates in a fail-open manner: request processing may continue after fatal input validation or body handling errors, instead of being safely aborted. [file:93]\n\nThe issue is compounded by the handler\u0027s deserialization call, which passes `policyDataSubscription` directly to `openapi.Deserialize(...)` instead of passing a pointer to the destination object. This inconsistent usage further increases the risk that request processing continues with an empty, partially initialized, or otherwise unintended subscription object. [file:93]\n\nThis differs from safer handlers in the same file, which use a helper pattern that explicitly returns on body read or deserialization failure before calling the corresponding processor routine. [file:93]\n\n### Security Impact\nThis issue affects a write-capable API that updates Policy Data notification subscriptions identified by `subsId`. [file:93]  \nBecause execution continues after body read or parsing failure, the processor may receive an uninitialized, partially initialized, or otherwise unintended `PolicyDataSubscription` object for persistence. [file:93]\n\nThe exact runtime impact depends on downstream processor behavior and storage validation. [file:93]  \nAt minimum, this is a security-relevant robustness flaw that can lead to inconsistent request handling or unintended modification attempts; under certain runtime conditions it may allow updates that should not be processed after an input error. [file:93]\n\n### Reproduction Status\nThe code path has been statically confirmed. [file:93]  A complete runtime proof of unintended subscription modification after\n`GetRawData()` or deserialization failure has not yet been established. [file:93]\n\n### Patch\nThe handler should immediately terminate after sending an error response for body read or deserialization failure. [file:93]\n\nA minimal fix is to add missing `return` statements in `HandlePolicyDataSubsToNotifySubsIdPut` and pass a pointer to the destination\nobject during deserialization: [file:93]\n\n```go\nreqBody, err := c.GetRawData()\nif err != nil {\n    logger.DataRepoLog.Errorf(\"Get Request Body error: %+v\", err)\n    pd := openapi.ProblemDetailsSystemFailure(err.Error())\n    c.Set(sbi.IN_PB_DETAILS_CTX_STR, pd.Cause)\n    c.JSON(http.StatusInternalServerError, pd)\n    return\n}\n\nerr = openapi.Deserialize(\u0026policyDataSubscription, reqBody, \"application/json\")\nif err != nil {\n    logger.DataRepoLog.Errorf(\"Deserialize Request Body error: %+v\", err)\n    pd := util.ProblemDetailsMalformedReqSyntax(err.Error())\n    c.Set(sbi.IN_PB_DETAILS_CTX_STR, pd.Cause)\n    c.JSON(http.StatusBadRequest, pd)\n    return\n}\n```",
  "id": "GHSA-gx38-8h33-pmxr",
  "modified": "2026-04-24T20:35:11Z",
  "published": "2026-04-14T20:00:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/free5gc/free5gc/security/advisories/GHSA-gx38-8h33-pmxr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40249"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/free5gc/udr"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "free5gc UDR fail-open request handling in PolicyDataSubsToNotifySubsIdPut may allow unintended subscription updates after input errors"
}

Sightings

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Nomenclature

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Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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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-2026-40249 (GCVE-0-2026-40249)

FKIE_CVE-2026-40249

GHSA-GX38-8H33-PMXR

Summary

Details

Security Impact

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Patch

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