Summary
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-subscriptionsendpoint with a malformed URL path containing path traversal sequences (../) and a large JSON payload. TheDataChangeNotificationProcedurefunction innotifier.goattempts 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.
Impact
The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-33064? CVE-2026-33064 is a high-severity null pointer dereference vulnerability in github.com/free5gc/udm (go), affecting versions < 1.4.2. It is fixed in 1.4.2. The application dereferences a null pointer, causing a crash.
- Which versions of github.com/free5gc/udm are affected by CVE-2026-33064? github.com/free5gc/udm (go) versions < 1.4.2 is affected.
- Is there a fix for CVE-2026-33064? Yes. CVE-2026-33064 is fixed in 1.4.2. Upgrade to this version or later.
- Is CVE-2026-33064 exploitable, and should I be worried? Whether CVE-2026-33064 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-33064 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-33064? Upgrade
github.com/free5gc/udmto 1.4.2 or later.