From upstream changelog:
"Fix a potential out of bounds write when checking a maliciously corrupted file system. This is probably not exploitable on 64-bit platforms, but may be exploitable on 32-bit binaries depending on how the compiler lays out the stack variables. (Addresses CVE-2019-5188)"
Likely low severity, but FWIW I wouldn't necessarily trust the "probably not exploitable".
We already have 1.45.5 in the tree, just needs to be stabilized.