CVE-2026-56818

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 0.5% (38th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 6.5Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
6.5
EG Score
6.5MEDIUMmedium confidence
EG Risk
60
EG Risk 60/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity65% × 45%
Exploitation40% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
38th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 7, 2026

Last Modified

September 23, 2026

Advisory Details (4)

Auto-updated Aug 7, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_pr, github.
github Patch Available🟡 PoC Available

RedisArrayAggregator max-elements failure leaves retained partial aggregate state · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-p9jm-q85p-7mcp
github_pr Patch Available

Merge branches from forks (#17063)

Patch available: netty/netty netty-4.1.136.Final (PR #17065 merged 2026-07-08)

https://github.com/netty/netty/pull/17065
github_commit Patch Available

commit bb2ff68a1fb7 (netty/netty)

Patch available: netty/netty netty-4.1.136.Final (contains commit bb2ff68a1fb7)

https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6
github_commit Patch Available

commit 5b68c61f37aa (netty/netty)

Patch available: netty/netty netty-4.2.16.Final (contains commit 5b68c61f37aa)

https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b

Vendor Advisories for CVE-2026-56818(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
netty1:4.1.48-10 ... 1:4.1.48-9 (16 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
netty1:4.1.48-10 ... 1:4.1.48-9 (12 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
netty1:4.1.48-10 ... 1:4.1.48-16 (8 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
netty1:4.1.48-10 ... 1:4.1.48-16 (7 versions)
  • every version on: no fix on record
—
Maven(1)
PackageVulnerable rangeFix by version rangeDependents
io.netty:netty-codec-redis4.2.0.Final ... 4.2.9.Final (16 versions)
  • every version up to 4.1.136.Final: fixed in 4.1.136.Final
  • 4.2.0-Final up to 4.2.16.Final: fixed in 4.2.16.Final
—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 47× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-05 08:14 UTCEG score recompute
  2. 2026-10-04 23:22 UTCEPSS rescore
  3. 2026-10-04 05:43 UTCEG score recompute
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  19. 2026-09-23 16:00 UTCEG score recompute
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  1. 2026-09-18 08:10 UTCEG score recompute
  2. 2026-09-17 19:31 UTCEPSS rescore
  3. 2026-09-17 10:12 UTCEG score recompute
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  10. 2026-09-13 16:47 UTCEPSS rescore
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  20. 2026-09-06 22:27 UTCEG score recompute
  21. 2026-09-06 13:47 UTCEPSS rescore
  22. 2026-09-06 00:26 UTCEG score recompute
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  24. 2026-09-04 05:07 UTCEPSS rescore
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  26. 2026-09-02 14:12 UTCEPSS rescore
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  30. 2026-09-01 04:40 UTCEPSS rescore
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  32. 2026-08-30 19:17 UTCEPSS rescore
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  34. 2026-08-30 01:22 UTCEPSS rescore
  35. 2026-08-29 10:23 UTCEG score recompute
  36. 2026-08-28 21:42 UTCEPSS rescore
  37. 2026-08-28 11:53 UTCEG score recompute
  38. 2026-08-27 14:25 UTCEPSS rescore
  39. 2026-08-27 11:32 UTCEG score recompute
  40. 2026-08-26 14:46 UTCEPSS rescore
  41. 2026-08-25 15:33 UTCEG score recompute
  42. 2026-08-25 13:49 UTCEPSS rescore
  43. 2026-08-24 17:33 UTCEG score recompute
  44. 2026-08-23 18:05 UTCEG score recompute
  45. 2026-08-23 00:19 UTCEPSS rescore
  46. 2026-08-22 20:07 UTCEG score recompute
  47. 2026-08-21 23:49 UTCEPSS rescore
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  49. 2026-08-20 22:55 UTCEPSS rescore
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  51. 2026-08-19 17:04 UTCEPSS rescore
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  53. 2026-08-18 13:48 UTCEPSS rescore
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  55. 2026-08-17 13:47 UTCEPSS rescore
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  57. 2026-08-16 14:56 UTCEPSS rescore
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  59. 2026-08-16 02:14 UTCEPSS rescore
  60. 2026-08-15 12:13 UTCEG score recompute
  61. 2026-08-15 01:30 UTCEPSS rescore
  62. 2026-08-14 14:14 UTCEG score recompute
  63. 2026-08-13 22:00 UTCEPSS rescore
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  66. 2026-08-11 20:17 UTCEG score recompute
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  68. 2026-08-10 00:20 UTCEG score recompute
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  74. 2026-08-07 18:26 UTCEG score recompute
  75. 2026-08-07 17:27 UTCEG score recompute

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-56818?
CVE-2026-56818 is a medium vulnerability published on August 7, 2026. 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…
When was CVE-2026-56818 disclosed?
CVE-2026-56818 was first published on August 7, 2026, with the most recent update on September 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-56818 actively exploited?
CVE-2026-56818 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (38th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-56818?
CVE-2026-56818 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-56818?
A fix for CVE-2026-56818 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-56818 are linked in the Vendor Advisories panel on this page.

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