User-session denial of service via anomalous P-256 key

Improper exceptional-condition handling in Western Digital Sweet B Library before 2 allows remote attackers to interrupt one user session via a P-256 key. The point-scalar multiplication path returns an error for a public key whose X coordinate is zero but writes an invalid, unreduced field value to the output buffer before signaling that error. Reachability requires a consuming application to pass the anomalous key into shared-secret or point-multiplication routines and then mishandle the error or output; the reported effect is confined to an individual user and does not extend to other components.