HDF5 can dereference a null pointer when reading an attribute that contains an invalid variable-length datatype type tag. A crafted HDF5 file that includes such an attribute causes the library to crash as the file is processed, resulting in a denial of service. The vulnerability is a classic NULL pointer dereference, identified by CWE-476, and also involves improper loop bounds validation (CWE-617). No escalation of privileges or remote code execution is possible directly from the flaw.

The HDF Group’s HDF5 library is affected. Exact version information is not supplied; consequently all installations that use the current release chain potentially contain the flaw.

The CVSS score of 5.2 indicates moderate severity. The EPSS score of <1% suggests a very low exploitation probability, and the vulnerability is not listed in the CISA KEV catalog. The attack vector is local, requiring the attacker to provide a malicious HDF5 file to a process that reads it. Once the file is loaded, the crash occurs immediately, preventing further execution but not allowing arbitrary code execution. The overall risk remains moderate, primarily stemming from the availability impact to the hosting application.