Stack Buffer Overflow in OpenAirInterface UDM Causing Service Crash via Oversized Hex Strings

OpenAirInterface Core Network v2.2.1 has a stack-based buffer overflow vulnerability in the OAI CN5G UDM Nudm_UEAU Generate Authentication Data endpoint. The UDM passes attacker-controlled resynchronizationInfo.rand and auts values to conv::hex_str_to_uint8(), which converts arbitrary-length hex strings into fixed-size stack buffers without validating the destination size. An unauthenticated attacker with access to the SBI interface and a valid SUPI can submit an oversized value to overwrite adjacent stack memory, corrupt the stack canary, and terminate the UDM process.

An issue was discovered in OpenAirInterface5G 2.4.0 (nr-softmodem) in the E2SM-KPM RAN Function's PRB utilization metric calculation. The functions fill_RRU_PrbTotDl() and fill_RRU_PrbTotUl() in openair2/E2AP/RAN_FUNCTION/O-RAN/ran_func_kpm_subs.c (lines 182 and 197) compute PRB usage percentages by dividing by the difference of two consecutive total_prb_aggregate samples without checking for zero. When a malicious xApp sends a high volume of E42_RIC_SUBSCRIPTION_REQUESTs via the FlexRIC iApp (port 36422/SCTP), the E2 Agent generates KPM Indication reports at high frequency. If two consecutive sampling intervals yield identical PRB aggregate values, the divisor becomes zero, triggering SIGFPE and crashing the entire 5G base station process (nr-softmodem). This results in complete 5G cell service interruption for all connected UEs. No authentication is required.

OpenAirInterface V2.2.0 AMF crashes when it fails to decode the message. Not all decode failures result in a crash. But the crash is consistent for particular inputs. An example input in hex stream is 80 00 00 0E 00 00 01 00 0F 80 02 02 40 00 58 00 01 88.

A segmentation fault in openairinterface5g v2.1.0 allows attackers to cause a Denial of Service (DoS) via a crafted UE Context Modification response.