CVE-2024-56921
Published: 03 February 2025
Summary
CVE-2024-56921 is a high-severity Uncontrolled Resource Consumption (CWE-400) vulnerability in Open5Gs Open5Gs. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked in the top 23.2% of CVEs by exploit likelihood; 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 SC-5 (Denial-of-service Protection) and SI-11 (Error Handling).
Deeper analysis
CVE-2024-56921 is a denial-of-service vulnerability in Open5GS version 2.7.2, affecting the AMF (Access and Mobility Management Function) component. The issue stems from incorrect error handling in the gmm_state_exception() function when processing a Nausf_UEAuthentication_Authenticate response. Specifically, an InitialUEMessage or Registration request sent at a precise timing can trigger this flaw, causing the AMF to crash. The vulnerability is rated with a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and is associated with CWE-400 (Uncontrolled Resource Consumption).
The vulnerability can be exploited remotely over the network by unauthenticated attackers with no privileges or user interaction required. An attacker simply needs to send a crafted Registration request or InitialUEMessage at the exact moment when the AMF is expecting the authentication response, leading to an unhandled exception and process crash. Successful exploitation results in high-impact availability disruption, potentially denying service to legitimate UEs attempting to register on the 5G network.
Mitigation is available through a patch in Open5GS, as detailed in the commit at https://github.com/open5gs/open5gs/commit/f780f9af45c27b6f49987d96ba71dedb3dd85840. Additional details on the issue, including reproduction steps and discussion, are provided in the GitHub issue tracker at https://github.com/open5gs/open5gs/issues/3608. Security practitioners should update to a patched version of Open5GS beyond v2.7.2 to address this flaw.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2024-53450
Vulnerability details
An issue was discovered in Open5gs v2.7.2. InitialUEMessage, Registration request sent at a specific time can crash AMF due to incorrect error handling of gmm_state_exception() function upon receipt of the Nausf_UEAuthentication_Authenticate response.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CVE directly describes remote unauthenticated exploitation of an AMF application flaw (incorrect error handling) that crashes the process, matching T1499.004 Application or System Exploitation for DoS.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly addresses the incorrect error handling in the gmm_state_exception() function that causes the AMF to crash upon receipt of timed InitialUEMessage or Registration requests.
Requires timely flaw remediation through patching, as provided in the Open5GS commit fixing CVE-2024-56921.
Implements denial-of-service protections to mitigate remote unauthenticated attacks causing high-impact availability disruption in the AMF.