Vulnerability in Netty
CVE-2026-56818
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L.
EPSS exploit prediction
EPSS: 0.005 (40.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 40.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Netty — versions < 4.1.136.Final, >= 4.2.0-Final, < 4.2.16.Final
Weakness classification (CWE)
References
- github.com/netty/netty/security/advisories/GHSA-p9jm-q85p-7mcp (Exploit, Vendor Advisory)
- github.com/netty/netty/pull/17065 (Patch, Issue Tracking)
- github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b (Patch)
- github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6 (Patch)
Frequently asked questions
- What is CVE-2026-56818?
- CVE-2026-56818 is a medium-severity vulnerability in Netty, classified under Missing Release of Memory after Effective Lifetime. CVSS score: 6.5/10. Published 2026-08-07.
- How severe is CVE-2026-56818?
- Medium severity. CVSS v3 base score is 6.5 out of 10.