CVE-2026-44319

free5GC's NEF crashes via logger.Fatal on PFD notification delivery failure (attacker-controlled notifyUri)

Reachable assertion / fail-fast (CWE-617) inside an asynchronous notification delivery path, plus improper handling of an exceptional condition (CWE-755) (treating a transient outbound HTTP failure as fatal), plus missing input validation (CWE-20) on the attacker-supplied notifyUri. logger.Fatal is os.Exit(1)-equivalent in Go -- it skips Gin recovery, deferred cleanup, and connection draining; the whole NEF process terminates.

In v4.2.1, the trigger chain is reachable without an Authorization header because the NEF route groups used in the chain are themselves mounted without inbound auth middleware (free5gc/free5gc#858, free5gc/free5gc#859, free5gc/free5gc#862). So in the validation lab any party that can reach NEF on the SBI can:

• Submit the three-step trigger anonymously and immediately terminate the NEF process.
• Repeat the trigger after every restart to sustain the outage.
• Pick any unreachable notifyUri (refused port, blackholed IP, DNS-NXDOMAIN, broken TLS) -- the failure branch is the same Fatal, so partial fixes that block one URI do not close the family.

No Confidentiality impact (the failure returns no attacker-readable data). No persistent Integrity impact (NEF state is in-memory and is lost when the process dies). The whole impact concentrates in Availability: complete loss of NEF service via a single attacker-controlled notification target.

Affected: free5gc v4.2.1.

Upstream issue: https://github.com/free5gc/free5gc/issues/924
Upstream fix: https://github.com/free5gc/nef/pull/25

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2026-44319 has a CVSS score of 7.5 (High). The vector is network-reachable, no 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 (1.2.3); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-44319? CVE-2026-44319 is a high-severity improper input validation vulnerability in github.com/free5gc/nef (go), affecting versions < 1.2.3. It is fixed in 1.2.3. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2026-44319? CVE-2026-44319 has a CVSS score of 7.5 (High). 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/nef are affected by CVE-2026-44319? github.com/free5gc/nef (go) versions < 1.2.3 is affected.
4. Is there a fix for CVE-2026-44319? Yes. CVE-2026-44319 is fixed in 1.2.3. Upgrade to this version or later.
5. Is CVE-2026-44319 exploitable, and should I be worried? Whether CVE-2026-44319 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-2026-44319 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-2026-44319? Upgrade github.com/free5gc/nef to 1.2.3 or later.