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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

EPSS

• CVE-2026-56818: 0.47% estimated exploitation activity in the next 30 days; percentile 40.95 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary RedisArrayAggregator 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, 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. The supplied PoV proves both the retained ByteBuf reference and the stale parser state continuation. Technical Details RedisArrayAggregator.decode(...) retains non-array messages before adding them to depths.peek().children. In decodeRedisArrayHeader(...), the header.length() maxElements branch throws immediately: The immediately following nested-depth branch clears retained aggregate state before throwing: The missing cleanup…

Published by the source

7 Aug 2026, 17:16 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 16:54 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-p9jm-q85p-7mcp

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-p9jm-q85p-7mcp

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# Patch Next advisory brief: CVE-2026-56818

Advisory: Netty: RedisArrayAggregator max-elements failure leaves retained partial aggregate state
IDs: CVE-2026-56818, GHSA-p9jm-q85p-7mcp
Record: https://patchnext.com/advisories/cve-2026-56818 (revision 2, source checked 26 Oct 2026, 16:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: io.netty:netty-codec-redis 4.2.16.Final, 4.1.136.Final. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven io.netty:netty-codec-redis: affected < 4.1.136.Final; >= 4.2.0-Final, < 4.2.16.Final; fixed in 4.2.16.Final, 4.1.136.Final

## Suggested inspection (read-only)
- Maven io.netty:netty-codec-redis: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on io.netty:netty-codec-redis.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-p9jm-q85p-7mcp (OSV record GHSA-p9jm-q85p-7mcp lists affected ranges: Maven io.netty:netty-codec-redis >=0 =4.2.0-Final <4.2.16.Final (fixed))
- Verified: https://github.com/advisories/GHSA-p9jm-q85p-7mcp (GitHub-reviewed advisory GHSA-p9jm-q85p-7mcp lists affected ranges: Maven io.netty:netty-codec-redis >=0 =4.2.0-Final <4.2.16.Final)

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