CVE-2026-59899

Netty HttpContentEncoder: Unbounded Per-Connection Queue Growth via HTTP/1.1 Pipelining Leads to Denial of Service

Published Jul 29, 2026 CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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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
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

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'}

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jul 30, 2026, 2:01 PM
Reserved
Jul 7, 2026, 4:40 PM
Status
Analyzed
Published
Jul 29, 2026, 6:16 PM
Modified
Aug 6, 2026, 8:25 PM
Severity
Important
Public date
Jul 9, 2026, 12:00 AM