CVE-2023-5678Network attack vector

Denial of service via unchecked DH parameters

Published Nov 6, 2023 · Updated May 12, 2026

Denial of service in affected OpenSSL releases allows remote attackers to cause long delays by supplying untrusted X9.42 DH data. DH_check_pub_key does not validate oversized P or Q parameters, while DH_generate_key checks P but not Q, causing disproportionately expensive computation. Exposure requires an application or command invocation to process untrusted X9.42 DH material; OpenSSL TLS and FIPS providers are unaffected.

CVSS severity5.3
Medium
EPSS probability4.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in affected OpenSSL releases allows remote attackers to cause long delays by supplying untrusted X9.42 DH data. DH_check_pub_key does not validate oversized P or Q parameters, while DH_generate_key checks P but not Q, causing disproportionately expensive computation. Exposure requires an application or command invocation to process untrusted X9.42 DH material; OpenSSL TLS and FIPS providers are unaffected.

The record

CVE
CVE-2023-5678
Published
Nov 6, 2023
Updated
May 12, 2026
Vendor
Siemens
Product
SINEC NMS
Classifications
CWE-606, CWE-754, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 6, 2023CVE publishedPublication date reported by the CVE source.
  2. May 12, 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=0 <V3.0 SP1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SINEC NMSversion=0 <V3.0 SP1
Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.0 <V3.1.5
OpenSSL Project · OpenSSLversion=1.0.2 <1.0.2zj; version=1.1.1 <1.1.1x; version=3.0.0 <3.0.13; version=3.1.0 <3.1.5
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SIDIS Primeversion=0 <V4.0.700

Published CVSS scores

5.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 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 exploitUnconfirmed

Weakness, pattern, technique

CWE-606Unchecked Input for Loop Condition
CWE-754Improper Check for Unusual or Exceptional Conditions
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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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