CVE-2026-1301Network attack vector

Process crash via JSON array overwrite

Published Feb 5, 2026 · Updated Feb 5, 2026

Out-of-bounds write in open62541 1.5-rc1 allows remote authenticated users to crash PubSub consumers with crafted JSON messages. The JSON PubSub decoder accepts attacker-controlled array structure and writes beyond a heap-allocated array while materializing the message, corrupting adjacent memory. Reachability requires a build with both PubSub and JSON enabled; exploitation interrupts the hosting process and requires active interaction.

CVSS severity6.8
Medium
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in open62541 1.5-rc1 allows remote authenticated users to crash PubSub consumers with crafted JSON messages. The JSON PubSub decoder accepts attacker-controlled array structure and writes beyond a heap-allocated array while materializing the message, corrupting adjacent memory. Reachability requires a build with both PubSub and JSON enabled; exploitation interrupts the hosting process and requires active interaction.

The record

CVE
CVE-2026-1301
Published
Feb 5, 2026
Updated
Feb 5, 2026
Vendor
o6 Automation GmbH
Product
open62541
Classifications
CWE-787, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 5, 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=1.5-rc1 <1.5-rc2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

o6 Automation GmbH · open62541version=1.5-rc1 <1.5-rc2

Published CVSS scores

6.8ICS-CERTCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499Endpoint Denial of Service

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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