Details for this vulnerability have not been published by NIST at this point. Descriptions from software vendor advisories for this issue are provided below.
Micah Snyder reports:
An out of bounds write was possible within ClamAV&s NSIS bzip2 library when attempting decompression in cases where the number of selectors exceeded the max limit set by the library (CVE-2019-12900). The issue has been resolved by respecting that limit.
The zip bomb vulnerability mitigated in 0.101.3 has been assigned the CVE identifier CVE-2019-12625. Unfortunately, a workaround for the zip-bomb mitigation was immediately identified. To remediate the zip-bomb scan time issue, a scan time limit has been introduced in 0.101.4. This limit now resolves ClamAV's vulnerability to CVE-2019-12625.