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Fencer Vulns
medium 6.5

CVE-2026-56818 json

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

published 2026-08-07 3 mo ago modified 2026-09-23 47 d ago also EUVD-2026-54558 , GHSA-p9jm-q85p-7mcp

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven io.netty:netty-codec-redis 4.1.136.Final, 4.2.16.Final
  • io.netty netty-codec-redis 4.1.136.Final, 4.2.16.Final
  • netty netty 4.1.136.Final, 4.2.16.Final
  • netty-tcnative SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.0.80-150200.3.48.1
  • netty SLE Module for Package Hub 15 SP7 4.1.136-150200.4.53.1

suse advisories SUSE-SU-2026:3482-1

  • netty openSUSE Tumbleweed 4.1.136-1.1

opensuse advisories openSUSE-SU-2026:11394-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-56818 updated cvss 7.5

io.netty/netty-codec-redis: Netty: Memory leak in netty-codec-redis

  • Red Hat build of Apache Camel for Spring Boot 4 netty-codec-redis 4.1.135.Final-redhat-00001 Red Hat Data Grid 8 netty-codec-redis 4.1.135.Final-redhat-00001
    affected: workaround, no fix available “Fix deferred”
  • Red Hat JBoss Enterprise Application Platform 7 eap74-els-openjdk8-openshift-rhel8, eap74-els-openjdk11-openshift-rhel8, eap74-els-openjdk17-openshift-rhel8, netty-codec-redis 4.1.135.Final-redhat-00001, jboss-eap-7-eap74-els-openjdk8-openshift-rhel8, jboss-eap-7-eap74-els-openjdk17-openshift-rhel8
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat JBoss Enterprise Application Platform Expansion Pack netty-codec-redis 4.1.135.Final-redhat-00001
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Single Sign-On 7 netty-codec-redis 4.1.135.Final-redhat-00001
    affected: workaround, no fix planned “Out of support scope”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/netty/netty/security/advisories/GHSA-p9jm-q85p-7mcp referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Affected packages

ecosystem package affected fixed in
maven io.netty:netty-codec-redis
<4.1.136.Final
>=4.2.0-Final, <4.2.16.Final
4.1.136.Final
4.2.16.Final

Affected products

  • netty netty

Classification

Weakness
  • CWE-401 Missing Release of Memory after Effective Lifetime
  • CWE-703 Improper Check or Handling of Exceptional Conditions

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.