CVE-2026-1973
Published: 06 February 2026
Summary
CVE-2026-1973 is a medium-severity Improper Resource Shutdown or Release (CWE-404) vulnerability in Free5Gc Free5Gc. Its CVSS base score is 5.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 35.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-11 (Error Handling).
Deeper analysis
CVE-2026-1973 is a null pointer dereference vulnerability affecting Free5GC versions up to 4.1.0, specifically in the establishPfcpSession function within the SMF (Session Management Function) component. This flaw, classified under CWE-404 and CWE-476, allows manipulation that triggers a crash due to improper handling of a null pointer. The issue carries a CVSS v3.1 base score of 5.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L), indicating moderate severity primarily impacting availability.
Remote attackers require only network access and face low complexity with no authentication or user interaction needed to exploit it. Successful exploitation results in a denial-of-service condition through application crashes, disrupting SMF operations in Free5GC deployments without affecting confidentiality or integrity.
Advisories recommend applying patches to mitigate the issue, with a fix available via pull request #189 in the free5gc/smf repository. Relevant discussions and the disclosed exploit details are documented in GitHub issues #815 and related threads.
The exploit has been publicly disclosed, enabling potential utilization by adversaries targeting Free5GC implementations.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-5605
Vulnerability details
A vulnerability was determined in Free5GC up to 4.1.0. The impacted element is the function establishPfcpSession of the component SMF. Executing a manipulation can lead to null pointer dereference. The attack may be launched remotely. The exploit has been publicly…
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disclosed and may be utilized. It is best practice to apply a patch to resolve this issue.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Null pointer dereference in network-reachable SMF function directly enables remote application crash, mapping to application exploitation for endpoint DoS.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Input validation in establishPfcpSession would reject malformed PFCP messages that trigger the null dereference.
Robust error handling would catch the null pointer in establishPfcpSession instead of crashing the SMF.
Flaw remediation directly requires applying the available patch (PR #189) that fixes the null dereference.