CVE-2026-51218Public exploitNetwork attack vector

Server crash via unchecked WriteVar item count

Published Jun 29, 2026 · Updated Jun 29, 2026

Heap buffer overflow in Snap7 1.4.3 allows remote attackers to crash the server process with a malformed S7 WriteVar request. TS7Worker::PerformFunctionWrite() trusts the request-declared ItemsCount and reads DataLength from item records beyond the received payload. Remote attackers need network reachability to the Snap7 server; the demonstrated consequence is a process crash without reported data disclosure or modification.

CVSS severity7.5
High
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in Snap7 1.4.3 allows remote attackers to crash the server process with a malformed S7 WriteVar request. TS7Worker::PerformFunctionWrite() trusts the request-declared ItemsCount and reads DataLength from item records beyond the received payload. Remote attackers need network reachability to the Snap7 server; the demonstrated consequence is a process crash without reported data disclosure or modification.

The record

CVE
CVE-2026-51218
Published
Jun 29, 2026
Updated
Jun 29, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-122, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 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?

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 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 exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
T1499Endpoint Denial of Service

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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