In all versions of libyang before 1.0-r5, a stack-based buffer overflow was discovered in the way libyang parses YANG files with a leaf of type "identityref". An application that uses libyang to parse untrusted YANG files may be vulnerable to this flaw, which would allow an attacker to cause a denial of service or possibly gain code execution.
CWE-787 - Out-of-Bounds Write
Out-of-bounds write vulnerability is a memory access bug that allows software to write data past the end or before the beginning of the intended buffer. This may result in the corruption of data, a crash, or arbitrary code execution.