Critical Redis RCE (CVE-2025-49844): Technical Breakdown & Action Plan

A critical, high-impact vulnerability has been discovered in Redis, one of the most ubiquitous in-memory data stores used in modern application architectures. Tracked as CVE-2025-49844, this flaw is a Lua sandbox escape that allows a remote attacker to achieve full Remote Code Execution (RCE) on the host server.

With a CVSS score of 9.9 (Critical), this is not a theoretical or low-impact bug. For a vast number of common, real-world deployments, this vulnerability is unauthenticated. An attacker needs nothing more than network access to a vulnerable Redis instance to take complete control.

Discovered by security researchers at Wiz, this vulnerability strikes at the heart of Redis’s scripting engine. This is your technical, no-nonsense guide to understanding the flaw, identifying your exposure, and executing the necessary remediation steps right now.

The Threat: A Technical Breakdown of the Lua Sandbox Escape

To understand the vulnerability, you must first understand how Redis uses Lua. Redis is more than a simple key-value store; it allows for complex, atomic operations through server-side Lua scripting, typically via the EVAL command. To do this safely, the Lua engine is supposed to operate within a sandbox—a tightly restricted environment that prevents scripts from interacting with the underlying operating system. The sandbox is the wall between a database command and a system command.

CVE-2025-49844 completely shatters that wall.

The vulnerability allows an attacker to craft a malicious Lua script that, when executed by the Redis server, breaks out of the intended sandboxed environment. This “sandbox escape” gives the attacker’s script the ability to execute arbitrary commands directly on the host operating system with the full privileges of the Redis server process.

If your Redis server is running as the redis user, the attacker gets control of that user. If your server is misconfigured and running as root—a dangerously common practice—the attacker gets immediate, full root access to your machine.

Are You Affected? The Critical Checklist

You are at high risk if you meet the following criteria:

• Product: You are running Redis.
• Vulnerable Versions: You are running a version prior to the following patched releases:
  • 7.2.6
  • 8.0.9
  • 8.2.2 (Essentially, if you are not on one of these versions or newer, you should assume you are vulnerable).
• Exposure: Your Redis server’s port (default: 6379/TCP) is accessible to an untrusted network. This includes:
  • Internet-facing instances: This is a critical misconfiguration and the highest-risk scenario.
  • Internal instances in a flat network: Where a compromise of a single, low-value machine can be used to pivot and attack the internal Redis server.

Crucially, authentication is not a guaranteed mitigation. While having a password on your Redis instance is a critical security layer, this vulnerability allows for privilege escalation even in authenticated environments. However, the most urgent threat is to the vast number of unauthenticated Redis instances exposed on the internet and in internal networks.

The Impact: From Data Store to Attacker Stronghold

A successful exploit of CVE-2025-49844 gives an attacker a complete system takeover. With RCE, an attacker can:

• Steal and Destroy Data: Gain direct access to all data stored within the Redis instance and connected databases.
• Deploy Persistent Backdoors: Install webshells, reverse shells, or other malware to maintain long-term access.
• Launch a Ransomware Attack: Use their foothold to encrypt the server and demand a ransom.
• Pivot for Lateral Movement: Use the compromised server as a trusted internal host to attack other systems within your network.
• Abuse Cloud Credentials: If running on a cloud instance, the attacker can steal the instance metadata credentials and potentially compromise your entire cloud environment.

The Action Plan

PATCH

The Redis maintainers have released patched versions that completely fix this vulnerability. This is the only definitive solution and must be your top priority.

Action: Upgrade all of your Redis instances to the latest patched version immediately.

• Upgrade to 6.2.20, 7.2.11, 7.4.6, 8.0.4, 8.2.2 or a newer stable release.

Refer to the official Redis GitHub release page for the latest versions and the security advisory for full details.

MITIGATE: If You Cannot Patch Immediately

If patching is not immediately possible due to operational constraints, you must implement the following compensating controls to reduce your risk.

Action:

• Firewall Your Redis Instances: This is non-negotiable. Ensure that your Redis port (6379) is not exposed to the internet. Use firewalls, security groups, and network ACLs to restrict access to only the specific application servers that absolutely require a connection. The default policy should be to deny all access.
• Prevent Lua Execution: For systems that cannot immediately update, a workaround is available by preventing users from executing Lua scripts through ACL restrictions on EVAL and EVALSHA commands

Warning: These are temporary measures. A determined attacker who gains a foothold elsewhere in your network could still find a way to exploit this vulnerability. Patching is the only permanent solution.

Conclusion: A Critical Reminder for a Ubiquitous Tool

CVE-2025-49844 is a stark reminder that even our most trusted and widely used infrastructure components can harbor critical flaws. The combination of a sandbox escape with the common misconfiguration of unauthenticated access creates a perfect storm for attackers.

The playbook for defenders is clear and urgent: Patch your Redis instances immediately. If you can’t, isolate them from all untrusted networks and enforce strong authentication. And finally, hunt for any signs that you may have already been compromised. In the face of a threat this critical, speed and decisiveness are your greatest assets.

To further enhance your cloud security and implement Zero Trust, contact me on LinkedIn Profile or [email protected].

Redis RCE FAQ (CVE-2025-49844)

• What is CVE-2025-49844? It is a critical (CVSS 9.9) Remote Code Execution vulnerability in Redis. It’s a Lua sandbox escape that allows an attacker to break out of the Redis scripting environment and execute arbitrary commands on the underlying server.
• Does an attacker need a username and password? Not in many common configurations. If a Redis instance is configured without authentication (the default in some older versions and a common setup in internal networks), an attacker only needs network access to the Redis port to achieve unauthenticated RCE.
• What is a “Lua sandbox escape”? Redis uses the Lua language for scripting. A “sandbox” is a security mechanism designed to restrict what the script can do, preventing it from accessing the host operating system. A “sandbox escape” is a vulnerability that allows a malicious script to bypass these restrictions and execute commands on the host.
• What is the immediate fix? You must upgrade your Redis instances to a patched version: 6.2.20, 7.2.11, 7.4.6, 8.0.4, 8.2.2 or a newer stable release. This is the only permanent fix.
• My Redis server is not on the internet. Am I safe? You are safer, but not completely safe. An attacker who compromises another machine on your internal network could use that machine to pivot and attack your unpatched Redis server. The best practice is to both patch the server and restrict network access to it, even on internal networks.

Relevant Resource List

• Wiz Blog: “Wiz Research Discovers Critical RCE Vulnerability in Redis (CVE-2025-49844)”
• Wiz Vulnerability Database: “CVE-2025-49844”
• Official Redis GitHub Security Advisory: GHSA-4789-qfc9-5f9q
• Redis 8.2.2 Release Notes: (Example of a patched version release)
• NVD: “CVE-2025-49844 Detail”