CVE-2026-23631
Description
A flaw was found in Redis, an in-memory data structure store. An authenticated attacker can exploit a use-after-free vulnerability in redis-server with Lua scripting. This occurs through the master-replica synchronization mechanism on replicas where replica-read-only is disabled or can be disabled. Successful exploitation may lead to remote code execution.
Statement
This Important vulnerability in Redis affects instances configured with Lua scripting and operating as replicas where the replica-read-only setting is disabled or can be modified by an authenticated attacker. Exploitation of a use-after-free flaw during master-replica synchronization could lead to remote code execution. The risk is present in deployments where Redis replicas are configured for write operations or lack sufficient access controls to prevent modification of the replica-read-only setting.
Mitigation
To mitigate this flaw, ensure that Redis replicas maintain `replica-read-only` as enabled and prevent its modification by unauthorized users. If Lua scripting is not a required feature, consider disabling it to reduce the attack surface. Restricting network access to Redis instances to trusted clients can also limit exposure.
For Redis configuration, edit the `redis.conf` file to include or verify:
`replica-read-only yes`
After modifying the configuration, restart the Redis service for the changes to take effect. This action will temporarily interrupt service availability.
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 | 8.1 | 8.8 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | None | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
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:N/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
