CVE-2021-21309

An integer overflow was found in Redis. Redis 4.0 or newer uses a configurable limit for the maximum supported bulk input size. The default size is 512MB which is a safe value for all platforms. Authenticated Redis users could increase the bulk input size by changing the "proto-max-bulk-len" configuration parameter, leading to heap corruption and potentially remote code execution.

This issue only affects 32-bit Redis. Red Hat Enterprise Linux 8 and Red Hat Software Collections are not affected by this issue because they do not provide support for 32-bit Redis. The following products are not affected because the vulnerable component (Redis 4.0) is not being consumed:

• Red Hat Ansible Automation Platform
• Red Hat Ansible Tower
• Red Hat OpenStack Platform

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

As recommended in the upstream advisory, this issue can be mitigated by preventing clients from directly executing CONFIG SET:

• Using Redis 6.0 or newer, ACL configuration can be used to block the command.
• Using older versions, the rename-command configuration directive can be used to rename the command to a random string unknown to users, rendering it inaccessible.