CVE-2026-56745Network attack vector

Remote denial of service via unreleased request buffers

Published Jul 21, 2026 · Updated Jul 21, 2026

Denial of service in Netty 4.1.0.Final through 4.1.135.Final and 4.2.0.Final through 4.2.15.Final allows remote attackers to exhaust native memory. SpdyHttpDecoder stores a pooled request buffer after a nonfinal SYN_STREAM frame, then removes it without releasing it on RST_STREAM or oversize content. A reachable application must use the SPDY-to-HTTP handler; repeated aborted or oversized streams permanently consume native memory and can halt the service.

CVSS severity8.7
High
EPSS probability0.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Netty 4.1.0.Final through 4.1.135.Final and 4.2.0.Final through 4.2.15.Final allows remote attackers to exhaust native memory. SpdyHttpDecoder stores a pooled request buffer after a nonfinal SYN_STREAM frame, then removes it without releasing it on RST_STREAM or oversize content. A reachable application must use the SPDY-to-HTTP handler; repeated aborted or oversized streams permanently consume native memory and can halt the service.

The record

CVE
CVE-2026-56745
Published
Jul 21, 2026
Updated
Jul 21, 2026
Vendor
The Netty Project
Product
Netty
Classifications
CWE-400, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 21, 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=>= 4.1.0.Final, < 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=>= 4.1.0.Final, < 4.1.136.Final; version=>= 4.2.0.Final, < 4.2.16.Final

Published CVSS scores

8.7GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.002Service Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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