Netty prior 4.1.136.Final/4.2.16.Final RedisArrayAggregator decodeRedisArrayHeader allocation of resources

Summaryinfo

A vulnerability identified as problematic has been detected in Netty. The impacted element is the function decodeRedisArrayHeader of the component RedisArrayAggregator. The manipulation leads to allocation of resources. This vulnerability is listed as CVE-2026-56818. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in Netty. It has been rated as problematic. This issue affects the function decodeRedisArrayHeader of the component RedisArrayAggregator. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. The summary by CVE is:

Netty is an asynchronous, event-driven network application framework. Prior to 4.1.136.Final and 4.2.16.Final, the RedisArrayAggregator Redis codec clears retained partial aggregate state when the maxNestedArrayDepth limit is exceeded, but it does not clear the same state when the sibling maxElements limit is exceeded. A peer can start a valid RESP array, send a bulk string child, then send a nested array header longer than the configured maxElements. Netty throws a decoder exception in decodeRedisArrayHeader, but the existing partial aggregate remains retained in the handler. If the application leaves the channel alive after the exception, later messages are still consumed into the pre-error aggregate, allowing an unauthenticated peer to keep attacker-controlled aggregate state alive across a security-limit exception and pin retained pooled buffers. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-56818 since 06/23/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 4.1.136.Final or 4.2.16.Final eliminates this vulnerability.

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• Netty

Website

• Product: https://github.com/netty/netty/

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