CVE-2026-33064: Github.com/free5gc/udm Free5GC UDM DataChangeNotification Procedure Panic Vulnerability

HIGH
Advisory Identifier: GHSA-7g27-v5wj-jr75
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CWE-476 CWE-478
Published
Advisory Summary

CVE-2026-33064 is a HIGH free5gc udm datachangenotification procedure panic vulnerability (CWE-476: NULL Pointer Dereference) affecting Github.com/free5gc/udm libraries in the Go ecosystem. The issue involves free5gc udm datachangenotification procedure panic due to nil pointer dereference. Remediation is available by upgrading affected packages to version 1.4.2.

CVE-2026-33064 at a Glance

CVE Identifier CVE-2026-33064
GHSA Identifier GHSA-7g27-v5wj-jr75
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-476: NULL Pointer Dereference
Affected Product Github.com/free5gc/udm
Package Ecosystem Go
Published Date
Last Updated

How to Fix CVE-2026-33064

To remediate this vulnerability, upgrade all affected Github.com/free5gc/udm dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/free5gc/udm fixed: 1.4.2 
Upgrade github.com/free5gc/udm to 1.4.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/free5gc/udm

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-33064, inspect your project dependencies for Github.com/free5gc/udm:

inspect dependencies for github.com/free5gc/udm

Analyze the terminal output to locate any version of Github.com/free5gc/udm in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.4.2), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-476: NULL Pointer Dereference, where the product dereferences a pointer that it expects to be valid but is null. In Github.com/free5gc/udm, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

**Impact** This is a NULL Pointer Dereference vulnerability leading to Denial of Service. - **Security Impact**: A remote attacker can cause the UDM service to panic and crash by sending a crafted POST request to the `/sdm-subscriptions` endpoint with a malformed URL path containing path traversal sequences (`../`) and a large JSON payload. The `DataChangeNotificationProcedure` function in `notifier.go` attempts to access a nil pointer without proper validation, causing a complete service crash with "runtime error: invalid memory address or nil pointer dereference". - **Functional Impact**: The service crashes completely, requiring manual restart. All UDM functionality is disrupted until recovery. - **Affected Parties**: All deployments of free5GC v4.0.1 using the UDM HTTP callback functionality. **Patches** Yes, the issue has been patched. The fix is implemented in PR free5gc/udm#78. Users should upgrade to the next release of free5GC that includes this commit. **Workarounds** There is no direct workaround at the application level. The recommendation is to apply the provided patch or implement API gateway-level filtering to block requests containing path traversal sequences.

CVE-2026-33064 Affected Github.com/free5gc/udm Versions

1 component(s)
Fixed Versions:
1.4.2
Product / Package Ecosystem Affected Versions Fixed Version
github.com/free5gc/udm
golang/github.com/free5gc/udm
Go
< 1.4.2
1.4.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/free5gc/free5gc/security/advisories/GHSA-7g27-v5wj-jr75
NVD — CVE-2026-33064 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33064
Github.com/free5gc/udm Source Repository REPOSITORY
https://github.com/free5gc/free5gc/issues/781
Github.com/free5gc/udm Source Repository REPOSITORY
https://github.com/free5gc/udm/pull/78
Security Fix Commit FIX COMMIT
https://github.com/free5gc/udm/commit/65d7070f4bfd016864cbbaefbd506bbc85d2fa92
Github.com/free5gc/udm Source Repository REPOSITORY
https://github.com/free5gc/udm

Frequently Asked Questions

What is CVE-2026-33064?
CVE-2026-33064 is a security vulnerability in Github.com/free5gc/udm involving free5GC UDM DataChangeNotification Procedure Panic Due to Nil Pointer Dereference under CWE-476: NULL Pointer Dereference.
Which Github.com/free5gc/udm versions are affected?
Affected versions include releases prior to 1.4.2 across affected packages: github.com/free5gc/udm.
What version fixes CVE-2026-33064?
Upgrading to 1.4.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/free5gc/udm affected?
Yes, github.com/free5gc/udm is affected in releases prior to 1.4.2. Upgrade your dependency to 1.4.2 or later.
What CWE is associated with CVE-2026-33064?
CVE-2026-33064 is classified under CWE-476: NULL Pointer Dereference (The product dereferences a pointer that it expects to be valid but is NULL.).
How can I check Go dependencies for CVE-2026-33064?
Run the dependency tree command: 'inspect dependencies for github.com/free5gc/udm'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-7g27-v5wj-jr75",
  "modified" : "2026-03-20T21:24:03Z",
  "published" : "2026-03-18T20:06:36Z",
  "aliases" : [ "CVE-2026-33064" ],
  "summary" : "free5GC UDM DataChangeNotification Procedure Panic Due to Nil Pointer Dereference",
  "details" : "**Impact**  \nThis is a NULL Pointer Dereference vulnerability leading to Denial of Service.  \n- **Security Impact**: A remote attacker can cause the UDM service to panic and crash by sending a crafted POST request to the `/sdm-subscriptions` endpoint with a malformed URL path containing path traversal sequences (`../`) and a large JSON payload. The `DataChangeNotificationProcedure` function in `notifier.go` attempts to access a nil pointer without proper validation, causing a complete service crash with \"runtime error: invalid memory address or nil pointer dereference\".  \n- **Functional Impact**: The service crashes completely, requiring manual restart. All UDM functionality is disrupted until recovery.  \n- **Affected Parties**: All deployments of free5GC v4.0.1 using the UDM HTTP callback functionality.\n\n**Patches**  \nYes, the issue has been patched.  \nThe fix is implemented in PR free5gc/udm#78.  \nUsers should upgrade to the next release of free5GC that includes this commit.\n\n**Workarounds**  \nThere is no direct workaround at the application level. The recommendation is to apply the provided patch or implement API gateway-level filtering to block requests containing path traversal sequences.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/free5gc/udm"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.4.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/free5gc/free5gc/security/advisories/GHSA-7g27-v5wj-jr75"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33064"
  }, {
    "type" : "WEB",
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  }, {
    "type" : "WEB",
    "url" : "https://github.com/free5gc/udm/pull/78"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/free5gc/udm/commit/65d7070f4bfd016864cbbaefbd506bbc85d2fa92"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/free5gc/udm"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-476", "CWE-478" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-18T20:06:36Z",
    "nvd_published_at" : "2026-03-20T08:16:12Z"
  }
}