CVE-2021-21309
Description
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.
Statement
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
Mitigation
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.8 | 8.8 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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