CyberSecBulletin
CVE-2023-36521NVD status: Modified

SIMATIC MV540 H: Allocation of Resources Without Limits or Throttling

Published Updated By the CyberSecBulletin desk

CVE-2023-36521 is a high-severity allocation of resources without limits or throttling vulnerability in SIMATIC MV540 H from Siemens, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version V3.3.4 as the first without the flaw, so updating SIMATIC MV540 H to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.63% chance of exploitation within 30 days, higher than 51% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update SIMATIC MV540 H to V3.3.4 or a later version.
  2. Update SIMATIC MV540 S to V3.3.4 or a later version.
  3. Update SIMATIC MV550 H to V3.3.4 or a later version.
  4. Read the advisory on cert-portal.siemens.com for workarounds and exact fixed builds.
  5. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
SiemensSIMATIC MV540 HAll versions < V3.3.4; before V3.3.4V3.3.4
SiemensSIMATIC MV540 SAll versions < V3.3.4; before V3.3.4V3.3.4
SiemensSIMATIC MV550 HAll versions < V3.3.4; before V3.3.4V3.3.4
SiemensSIMATIC MV550 SAll versions < V3.3.4; before V3.3.4V3.3.4
SiemensSIMATIC MV560 UAll versions < V3.3.4; before V3.3.4V3.3.4
SiemensSIMATIC MV560 XAll versions < V3.3.4; before V3.3.4V3.3.4
SiemensSimatic Mv540 H Firmwarebefore 3.3.43.3.4
SiemensSimatic Mv540 S Firmwarebefore 3.3.43.3.4
SiemensSimatic Mv550 H Firmwarebefore 3.3.43.3.4
SiemensSimatic Mv550 S Firmwarebefore 3.3.43.3.4
SiemensSimatic Mv560 U Firmwarebefore 3.3.43.3.4
SiemensSimatic Mv560 X Firmwarebefore 3.3.43.3.4

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.6HighCNA (siemens.com)
CVSS 3.17.5HighNVD

Official description

A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3.4), SIMATIC MV540 S (All versions < V3.3.4), SIMATIC MV550 H (All versions < V3.3.4), SIMATIC MV550 S (All versions < V3.3.4), SIMATIC MV560 U (All versions < V3.3.4), SIMATIC MV560 X (All versions < V3.3.4). The result synchronization server of the affected products contains a vulnerability that may lead to a denial of service condition. An attacker may cause a denial of service situation of all socket-based communication of the affected products if the result server is enabled.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Allocation of Resources Without Limits or Throttling

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

How developers prevent this class of flaw

  • Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
  • Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
  • For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

More Allocation of Resources Without Limits or Throttling vulnerabilities (CWE-770)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in SIMATIC MV540 H

All SIMATIC MV540 H vulnerabilities

Recent Allocation of Resources Without Limits or Throttling vulnerabilities

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