CVE-2026-67856Public exploitNetwork attack vector

Server crash via stale subscription back-pointers

Published Aug 4, 2026 · Updated Aug 4, 2026

Heap use-after-free in open62541 1.5.5 and earlier allows remote attackers to crash OPC UA servers through crafted subscription requests. Operation_TransferSubscription shallow-copies UA_Subscription but rebuilds only monitoredItems, leaving samplingMonitoredItems back-pointers aimed at the old object. A client that creates a sampling monitored item, queues Publish, transfers the subscription, and deletes it triggers a stale-pointer write and server crash.

CVSS severity7.5
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

Heap use-after-free in open62541 1.5.5 and earlier allows remote attackers to crash OPC UA servers through crafted subscription requests. Operation_TransferSubscription shallow-copies UA_Subscription but rebuilds only monitoredItems, leaving samplingMonitoredItems back-pointers aimed at the old object. A client that creates a sampling monitored item, queues Publish, transfers the subscription, and deletes it triggers a stale-pointer write and server crash.

The record

CVE
CVE-2026-67856
Published
Aug 4, 2026
Updated
Aug 4, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA ADPCVSS: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.

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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 exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

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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