There is 1 open security issue in buster.
1 issue left for the package maintainer to handle:
(postponed; to be fixed through a stable update)
Squid through 4.14 and 5.x through 5.0.5, in some configurations, allows information disclosure because of an out-of-bounds read in WCCP protocol data. This can be leveraged as part of a chain for remote code execution as nobody.
You can find information about how to handle this issue in the security team's documentation.