CVE-2021-32626
Description
A heap buffer overflow was found in redis. Specially crafted Lua scripts executing in Redis cause the heap-based Lua stack to overflow due to incomplete checks for this condition. This flaw allows a remote attacker to corrupt the heap and potentially trigger remote code execution. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.
Mitigation
Prevent users from executing Lua scripts. This can be done using ACL to restrict EVAL and EVALSHA commands. Please see https://redis.io/topics/acl for more information on how to do this.
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 | 7.5 | 8.8 | 7.5 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | Low | High |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/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
cve.org: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Red Hat CVSS v3 Score Explanation
The attacker must not only have at least PR:L, but also have access to the EVAL or EVALSHA commands, and perform complex operations to corrupt the heap and ultimately achieve remote code execution. For this reason, we have rated AC:H.
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
Acknowledgements
Upstream acknowledges Meir Shpilraien as the original reporter.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
