CVE-2026-25588: 
Redis vulnerability analysis and mitigation

CVE-2026-25588 is a heap-based buffer overflow vulnerability in the RedisTimeSeries module for Redis, affecting all versions before 1.12.14. The flaw exists in the module's handling of serialized values processed through the Redis RESTORE command, where insufficient input validation can trigger invalid memory access and potentially lead to remote code execution. It was published on May 5, 2026, and patched in version 1.12.14 released the same day. The vulnerability carries a CVSS v3.1 base score of 8.8 (High) and a CVSS v4.0 base score of 7.7 (High) (GitHub Advisory, Red Hat). It was discovered by a group of researchers known as "Skateboarding Dog" during the Wiz Zeroday Cloud event (GitHub Advisory).

The root cause is classified as CWE-122 (Heap-based Buffer Overflow) and CWE-20 (Improper Input Validation). The RedisTimeSeries module fails to properly validate serialized data when processing the Redis RESTORE command, allowing a crafted serialized payload to trigger unsafe memory accesses in the heap (GitHub Advisory). Exploitation requires the attacker to be authenticated to the Redis instance, have the RedisTimeSeries module loaded on the server, and possess permission to execute the RESTORE command. The attack vector is network-based with low privileges required and no user interaction needed (GitHub Advisory, Red Hat).

Successful exploitation allows an authenticated attacker to execute arbitrary code in the context of the Redis server process, potentially resulting in full system compromise, data exfiltration, unauthorized data modification, or service disruption. The vulnerability has high impact on confidentiality, integrity, and availability of the affected Redis instance (GitHub Advisory). Given that Redis servers often store sensitive application data and may be accessible from multiple internal services, a successful compromise could facilitate lateral movement within an environment (Redis Blog).

1. Reconnaissance: Identify Redis servers with the RedisTimeSeries module loaded, using network scanning tools (e.g., Shodan, Censys, or nmap targeting port 6379) and probing with MODULE LIST after authentication.
2. Authentication: Obtain valid Redis credentials through credential stuffing, leaked secrets, or misconfigured instances with no authentication (requirepass not set).
3. Verify RESTORE permissions: Confirm the authenticated user has permission to execute the RESTORE command by checking ACL rules (ACL WHOAMI, ACL LIST).
4. Craft malicious payload: Construct a specially crafted serialized payload that exploits the insufficient validation in the RedisTimeSeries module's deserialization logic, designed to trigger a heap-based buffer overflow.
5. Execute RESTORE command: Send the malicious payload via the Redis RESTORE command (e.g., RESTORE <key> 0 <crafted_serialized_payload>) to the target server.
6. Achieve code execution: The malformed payload triggers invalid memory access in the heap, potentially allowing arbitrary code execution in the context of the Redis server process (GitHub Advisory).

• Network: Unexpected or anomalous connections to Redis port (default 6379/tcp) from unusual source IPs; large or malformed RESTORE command payloads observed in network traffic captures.
• Logs: Redis server logs showing RESTORE command executions from unexpected or low-privilege users; crash logs or core dumps generated by the Redis process indicating memory access violations.
• Process: Unexpected child processes spawned by the Redis server process (e.g., shells, network utilities); Redis process consuming abnormal CPU or memory resources.
• File System: Unexpected files written to the Redis working directory or system temp directories; new cron jobs, SSH keys, or persistence mechanisms created under the Redis service account.

Upgrade RedisTimeSeries to version 1.12.14 or later, which contains the security fix for this vulnerability (GitHub Release). Note that starting with Redis 8, the time series data structure is integral to Redis and does not require a separate module installation. As a temporary workaround, restrict access to the RESTORE command using Redis ACL rules to limit which authenticated users can execute it (e.g., ACL SETUSER <username> -RESTORE) (GitHub Advisory). Additionally, enforce network-level controls to restrict Redis access to trusted hosts only, and ensure Redis is not exposed to the public internet.

Redis published an official security advisory blog post covering CVE-2026-25588 alongside four other CVEs disclosed in the same batch (Redis Blog). The Canadian Centre for Cyber Security (CCCS) issued an alert (AV26-423) covering the Redis security advisories (CCCS Advisory). Security news outlets including GBHackers, CyberSecurityNews, and CyberPress covered the Redis vulnerability batch, highlighting the RCE risk to exposed Redis servers (GBHackers, CyberSecurityNews). The Hong Kong CERT also issued a security bulletin covering multiple Redis vulnerabilities in the same disclosure (HKCERT).