Debian 11: DLA-4029-1 Critical: FRR Routing Performance Issue

In FRR, the internet routing protocol suite software, all routes are
re-validated if the total size of an update received via RTR exceeds the
internal socket's buffer size, default 4K on most OSes.

An attacker can use this to trigger re-parsing of the RIB for FRR routers
using RTR by causing more than this number of updates during an update
interval (usually 30 minutes). Additionally, this effect regularly occurs
organically. Furthermore, an attacker can use this to trigger route validation
continuously. Given that routers with large full tables may need more than
30 minutes to fully re-validate the table, continuous issuance/withdrawal of
large numbers of ROA may be used to impact the route handling performance of
all FRR instances using RPKI globally. Additionally, the re-validation will
cause heightened BMP traffic to ingestors.

For Debian 11 bullseye, this problem has been fixed in version
7.5.1-1.1+deb11u4.

We recommend that you upgrade your frr packages.