CVE-2026-63252Network attack vector

Pre-authentication server termination via retained UASC chunks

Published Aug 4, 2026 · Updated Aug 4, 2026

Denial of service in Eclipse Milo 0.6.0 through 1.1.4 allows remote attackers to terminate OPC UA servers via incomplete UASC chunks. The asymmetric and symmetric UASC server handlers retain Netty ByteBuf chunks for partial messages but do not release them when a channel becomes inactive or the handler is removed. Repeated unauthenticated connections that send an incomplete chunk and disconnect consume pooled direct memory until the JVM server process is terminated.

CVSS severity8.7
High
EPSS probability0.42%
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 Eclipse Milo 0.6.0 through 1.1.4 allows remote attackers to terminate OPC UA servers via incomplete UASC chunks. The asymmetric and symmetric UASC server handlers retain Netty ByteBuf chunks for partial messages but do not release them when a channel becomes inactive or the handler is removed. Repeated unauthenticated connections that send an incomplete chunk and disconnect consume pooled direct memory until the JVM server process is terminated.

The record

CVE
CVE-2026-63252
Published
Aug 4, 2026
Updated
Aug 4, 2026
Vendor
The Eclipse Foundation
Product
Eclipse Milo
Classifications
CWE-401, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=0.6.0 <=1.1.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Eclipse Foundation · Eclipse Miloversion=0.6.0 <=1.1.4

Published CVSS scores

8.7Eclipse FoundationCVSS: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 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-401Missing Release of Memory after Effective Lifetime
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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