CVE-2021-32675

Redis is an open source, in-memory database that persists on disk. When
parsing an incoming Redis Standard Protocol (RESP) request, Redis allocates
memory according to user-specified values which determine the number of
elements (in the multi-bulk header) and size of each element (in the bulk
header). An attacker delivering specially crafted requests over multiple
connections can cause the server to allocate significant amount of memory.
Because the same parsing mechanism is used to handle authentication
requests, this vulnerability can also be exploited by unauthenticated
users. The problem is fixed in Redis versions 6.2.6, 6.0.16 and 5.0.14. An
additional workaround to mitigate this problem without patching the
redis-server executable is to block access to prevent unauthenticated users
from connecting to Redis. This can be done in different ways: Using network
access control tools like firewalls, iptables, security groups, etc. or
Enabling TLS and requiring users to authenticate using client side
certificates.