CVE-2026-59899Network attack vector

Denial of service via unbounded encoding queue

Published Jul 29, 2026 · Updated Jul 29, 2026

Resource exhaustion in Netty before 4.1.136.Final and 4.2.0.Final through 4.2.15.Final allows remote attackers to interrupt service. HttpContentEncoder appends attacker-controlled request data to the per-channel acceptEncodingQueue without a size bound and drains it only for later non-1xx responses. An unauthenticated HTTP/1.1 client must pipeline requests faster than the application responds, causing memory consumption and service interruption.

CVSS severity6.9
Medium
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Netty before 4.1.136.Final and 4.2.0.Final through 4.2.15.Final allows remote attackers to interrupt service. HttpContentEncoder appends attacker-controlled request data to the per-channel acceptEncodingQueue without a size bound and drains it only for later non-1xx responses. An unauthenticated HTTP/1.1 client must pipeline requests faster than the application responds, causing memory consumption and service interruption.

The record

CVE
CVE-2026-59899
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
The Netty Project
Product
Netty
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.1.136.Final
  2. Affected versionversion=>= 4.2.0.Final, < 4.2.16.Final

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Netty Project · Nettyversion=< 4.1.136.Final; version=>= 4.2.0.Final, < 4.2.16.Final

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.9GitHub, Inc.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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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