CVE-2026-44323

free5GC's UDR nudr-dr DELETE amf-subscriptions panics on missing subsId when UE state exists (nil pointer dereference)

NULL pointer dereference (CWE-476) in an authenticated UDR data-repository handler, caused by improper handling of the missing-subsId branch (CWE-754): the handler sets a problem-details value but does not return, then dereferences the same missing map entry.

This is NOT framed as an auth-bypass finding: the endpoint requires a valid nudr-dr OAuth2 access token. A network attacker who already holds (or can obtain) a valid token can:

• Trigger a reliable, repeatable nil-deref panic on the amf-subscriptions delete route after one preparatory POST that allocates UE state for the chosen ueId.
• Repeat the trigger to sustain a per-request panic-DoS on UDR's data-repository surface, with each panic costing more CPU + log writes than the intended 404 SUBSCRIPTION_NOT_FOUND response would have.

No Confidentiality impact (the response is 500 with empty body; no UE data is returned to the attacker via the panic). No persistent Integrity impact from the panic itself (the EE subscription created during the precondition is in-memory state owned by UDR's intended data-repository semantics, and is not corrupted by the delete-time panic). Availability impact is limited to per-request degradation (Gin recovers; the UDR process keeps running).

Affected: free5gc v4.2.1.

Upstream issue: https://github.com/free5gc/free5gc/issues/919
Upstream fix: https://github.com/free5gc/udr/pull/60

The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.

CVE-2026-44323 has a CVSS score of 4.3 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.4.3); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-44323? CVE-2026-44323 is a medium-severity null pointer dereference vulnerability in github.com/free5gc/udr (go), affecting versions < 1.4.3. It is fixed in 1.4.3. The application dereferences a null pointer, causing a crash.
2. How severe is CVE-2026-44323? CVE-2026-44323 has a CVSS score of 4.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/free5gc/udr are affected by CVE-2026-44323? github.com/free5gc/udr (go) versions < 1.4.3 is affected.
4. Is there a fix for CVE-2026-44323? Yes. CVE-2026-44323 is fixed in 1.4.3. Upgrade to this version or later.
5. Is CVE-2026-44323 exploitable, and should I be worried? Whether CVE-2026-44323 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
6. What actually determines whether CVE-2026-44323 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.
7. How do I fix CVE-2026-44323? Upgrade github.com/free5gc/udr to 1.4.3 or later.