Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, `HttpContentEncoder` (the superclass of the production handler `HttpContentCompressor`) maintains a per-channel `ArrayDeque<CharSequence>` named `acceptEncodingQueue` that accumulates attacker-controlled data without any size limit. The queue is filled on the I/O thread for every inbound HTTP request and drained only when the application later writes a non-1xx response. This creates a resource exhaustion vulnerability when an attacker exploits HTTP/1.1 pipelining to flood the connection with requests faster than the application produces responses. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact Low

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
netty netty affected
Version Status Constraints
>= 4.2.0.Final, < 4.2.16.Final affected —
< 4.1.136.Final affected —

No data.

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Project Subscriptions

No data.

Advisories
Source ID Title
Github GHSA Github GHSA GHSA-q4f6-jm68-57ww Netty: [HttpContentEncoder] Unbounded Per-Connection Queue Growth via HTTP/1.1 Pipelining Leads to Denial of Service
Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/netty/netty/releases/tag/netty-4.1.136.Final cve-icon
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final cve-icon
https://github.com/netty/netty/security/advisories/GHSA-q4f6-jm68-57ww cve-icon cve-icon
https://netty.io/news/2026/07/09/4-1-136-Final.html cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-59899 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-59899 cve-icon
History

Wed, 29 Jul 2026 18:15:00 +0000

Type Values Removed Values Added
Description A flaw was found in the Netty netty-codec-http component. A remote attacker can send HTTP requests containing highly compressed data. The HTTP decoder in netty-codec-http fails to properly limit the decompression of this content, causing the system to consume excessive memory. This can lead to memory exhaustion and a denial of service (DoS), making the service unavailable to legitimate users. Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, `HttpContentEncoder` (the superclass of the production handler `HttpContentCompressor`) maintains a per-channel `ArrayDeque<CharSequence>` named `acceptEncodingQueue` that accumulates attacker-controlled data without any size limit. The queue is filled on the I/O thread for every inbound HTTP request and drained only when the application later writes a non-1xx response. This creates a resource exhaustion vulnerability when an attacker exploits HTTP/1.1 pipelining to flood the connection with requests faster than the application produces responses. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.
Title io.netty/netty-codec-http: Netty: Memory exhaustion in netty-codec-http (decompression bomb) Netty HttpContentEncoder: Unbounded Per-Connection Queue Growth via HTTP/1.1 Pipelining Leads to Denial of Service
Weaknesses CWE-770
References
Metrics cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}

Tue, 28 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
Description A flaw was found in the Netty netty-codec-http component. A remote attacker can send HTTP requests containing highly compressed data. The HTTP decoder in netty-codec-http fails to properly limit the decompression of this content, causing the system to consume excessive memory. This can lead to memory exhaustion and a denial of service (DoS), making the service unavailable to legitimate users.
Title io.netty/netty-codec-http: Netty: Memory exhaustion in netty-codec-http (decompression bomb)
Weaknesses CWE-409
References
Metrics threat_severity

None

 cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-29T18:00:37.588Z

Reserved: 2026-07-07T16:40:07.984Z

Link: CVE-2026-59899

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

Severity : Important

Publid Date: 2026-07-09T00:00:00Z

Links: CVE-2026-59899 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses