CVE-2026-37536:

A stack buffer overflow vulnerability exists in the `send_diagnostic_request` function of miaofng/uds-c (commit e506334e270d77b20c0bc259ac6c7d8c9b702b7a), allowing an adjacent network attacker to overflow a 6-byte stack buffer by up to 4 bytes due to missing bounds checking on `payload_length` before a `memcpy` operation.

CVE-2026-37536 is a stack-based buffer overflow (CWE-121) affecting the miaofng fork of the uds-c library at a specific historical commit. The vulnerable `send_diagnostic_request` function defines an internal stack buffer constrained to `MAX_DIAGNOSTIC_PAYLOAD_SIZE` (6 bytes) but permits a `memcpy` operation that can write up to 10 bytes into it when `payload_length` reaches its defined maximum of `MAX_UDS_REQUEST_PAYLOAD_LENGTH` (7 bytes). The write begins at a calculated offset within the buffer (`1 + pid_length`), meaning the overflow can exceed the buffer boundary by 4 bytes. Because no input validation or length check is performed on `payload_length` before the copy, an adjacent network attacker without any authentication or user interaction can trigger the overflow. The vulnerability carries a CVSS 3.1 score of 8.8 (HIGH), with potential impacts spanning full confidentiality loss, integrity compromise, and availability disruption on the affected system.