rpcapd/daemon.c in libpcap before 1.9.1 on non-Windows platforms provides details about why authentication failed, which might make it easier for attackers to enumerate valid usernames.
Created libpcap tracking bugs for this issue:
Affects: fedora-all [bug 1760624]
RPCAPD support added in tcpdump 1.9.0 (see https://github.com/the-tcpdump-group/libpcap/blob/libpcap-1.9/CHANGES#L74).
RHEL 6 and 7 ship an older version of libpcap that does not even have the vulnerable file.
RHEL 8 ships a newer version, however it is not compiled with RPCAPD support (--enable-remote is not specified).
This issue did not affect the versions of libpcap as shipped with Red Hat Enterprise Linux 6, 7, and 8 as they did not include support for RPCAPD.
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):