Skip to content
Fencer Intel
high 7.5

CVE-2023-27321 json

OPC Foundation UA .NET Standard ConditionRefresh Resource Exhaustion Denial-of-Service Vulnerability

published 3y ago modified 4mo ago also GHSA-vpf7-r2fv-75m9 , EUVD-2023-1630

cvss
7.5
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 64%
public exploits
0
none known

Summary

OPC Foundation UA .NET Standard ConditionRefresh Resource Exhaustion Denial-of-Service Vulnerability. This vulnerability allows remote attackers to create a denial-of-service condition on affected installations of OPC Foundation UA .NET Standard. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the handling of OPC UA ConditionRefresh requests. By sending a large number of requests, an attacker can consume all available resources on the server. An attacker can leverage this vulnerability to create a denial-of-service condition on the system. Was ZDI-CAN-20505.

Patch / fix

  • nuget OPCFoundation.NetStandard.Opc.Ua.Server 1.4.371.86
  • opcfoundation ua-.netstandard 1.4.371.86

Is CVE-2023-27321 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-24-165-06 updated cvss 7.5

Siemens TIM 1531 IRC

  • Siemens SIPLUS TIM 1531 IRC (6AG1543-1MX00-7XE0) <V2.4.8 Siemens TIM 1531 IRC (6GK7543-1MX00-0XE0) <V2.4.8
    affected: fixed in V2.4.8 support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2y ago

Exploit prediction

1.05% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-14).

CVSS scores

assigned by version score vector
CNA 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
nuget OPCFoundation.NetStandard.Opc.Ua.Server
<1.4.371.86
1.4.371.86

Affected products

  • OPC Foundation UA .NET Standard
  • opcfoundation unified_architecture_.net-standard

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.