CVE-2026-56818
MEDIUMCVE-2026-56818 is a medium-severity (CVSS 6.5) CWE-401 vulnerability. O3 Security confirms whether CVE-2026-56818 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
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…
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.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-56818 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-56818 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-56818. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-56818 in your dependencies?
O3 detects CVE-2026-56818 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.