Vulnerabilities

Heap-based buffer overflow in the SOHM list-index deserialization code in HDF5 through 2.1.1 on all platforms allows attackers to cause a denial of service (crash) via a crafted HDF5 file whose shared-message list index declares a num_messages count exceeding list_max, triggering out-of-bounds heap reads and writes in H5SM__cache_list_deserialize and H5SM__cache_list_verify_chksum.

HDF5 is a high-performance library and a file format specification that implements the HDF5 data model. If a file is corrupted such that an array datatype's size, the number of elements, and the element size are not in agreement it can trigger an out of bounds read. The array datatype stores the full size of the datatype (`dt->shared->size`) separately from the number of elements (`dt->shared->u.array.nelem`) and the element size (`dt->shared->parent->shared->size`). If any one of these are corrupted so that they don't align with the others (element size * nelem = full size), it can lead to an out of bounds read. Depending on what is corrupted, it can alter the type of out of bounds read triggered. The vulnerability is present only in files that have been maliciously altered, as its generally not possible to independently alter the full size of the datatype, the element count and the element size. As such, this is only present if a malicious actor is altering files, and won't appear in regular usage.