An assertion failure exists in the Open5GS SMF component when the smf_nudm_sdm_handle_get function receives a manipulated preemptCap argument. This flaw can cause the SMF process to crash, resulting in a denial of service. The weakness is a classic example of CWE‑617, where an internal assertion is improperly trusted without validating its preconditions.

The vulnerability affects Open5GS version 2.7.7 and earlier. The issue resides in the SMF service; specifically, the nudm-handler.c file. Upgrading the Open5GS installation to version 2.8.0 or later applies the necessary fix, as indicated by the referenced commit hash.

The CVSS score of 5.3 places this flaw in the medium severity range. No EPSS score is currently available, suggesting limited or unknown exploitation probability. The vulnerability is not listed in the CISA KEV catalog. An attacker can remotely trigger the flaw by sending a crafted request that manipulates the preemptCap value, leading to a service crash. The attack vector is remote and does not require local code execution or elevated privileges.