Vulnerability · Published Aug 7, 2026 · Assigned by GitHub_M

CVE-2026-56818Netty: RedisArrayAggregator max-elements failure leaves retained partial aggregate state

Medium 6.5

In plain English

A medium-severity memory leak in netty from netty. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium

Exploit odds (30 days)0.5%top 58.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	netty	no fix listed	DEBIAN-CVE-2026-56818
Debian:13	netty	no fix listed	DEBIAN-CVE-2026-56818
Debian:14	netty	no fix listed	DEBIAN-CVE-2026-56818
Maven	io.netty:netty-codec-redis	4.1.136.Final	GHSA-p9jm-q85p-7mcp
Maven	io.netty:netty-codec-redis	4.2.16.Final	GHSA-p9jm-q85p-7mcp
Ubuntu:26.10	netty	no fix listed	UBUNTU-CVE-2026-56818

Affected products (as reported)

Vendor	Product	Versions
netty	netty	< 4.1.136.Final>= 4.2.0-Final, < 4.2.16.Final

Weakness: CWE-401, CWE-703 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

References

https://github.com/netty/netty/security/advisories/GHSA-p9jm-q85p-7mcp x_refsource_CONFIRM
https://github.com/netty/netty/pull/17065 x_refsource_MISC
https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b x_refsource_MISC
https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6 x_refsource_MISC