CVE-2023-36521Network attack vector

Socket communication outage via unbounded resource allocation

Published Jul 11, 2023 · Updated Nov 21, 2024

Resource exhaustion in Siemens SIMATIC MV500 firmware before 3.3.4 allows remote attackers to interrupt all socket communication. The result synchronization server allocates resources without limits or throttling, but Siemens has not disclosed the triggering request or resource type. The server must be enabled; exploitation affects every socket-based service on the reader without requiring authentication.

CVSS severity8.6
High
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Siemens SIMATIC MV500 firmware before 3.3.4 allows remote attackers to interrupt all socket communication. The result synchronization server allocates resources without limits or throttling, but Siemens has not disclosed the triggering request or resource type. The server must be enabled; exploitation affects every socket-based service on the reader without requiring authentication.

The record

CVE
CVE-2023-36521
Published
Jul 11, 2023
Updated
Nov 21, 2024
Vendor
Siemens
Product
SIMATIC MV550 H
Classifications
CWE-770, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 11, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 21, 2024Record 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 <V3.3.4
  2. Affected versionversion=All versions < V3.3.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIMATIC MV550 Hversion=0 <V3.3.4; version=All versions < V3.3.4
Siemens · SIMATIC MV540 Sversion=0 <V3.3.4; version=All versions < V3.3.4
Siemens · SIMATIC MV560 Uversion=0 <V3.3.4; version=All versions < V3.3.4
Siemens · SIMATIC MV560 Xversion=0 <V3.3.4; version=All versions < V3.3.4
Siemens · SIMATIC MV550 Sversion=0 <V3.3.4; version=All versions < V3.3.4
Siemens · SIMATIC MV540 Hversion=0 <V3.3.4; version=All versions < V3.3.4

Published CVSS scores

8.6Siemens ProductCERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
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-770Allocation of Resources Without Limits or Throttling
T0814Denial 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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