CVE-2023-30756Network attack vector

Denial of service via HTTP Expect handling

Published Sep 10, 2024 · Updated Sep 10, 2024

NULL pointer dereference in web servers across Siemens SIMATIC products allows remote attackers to cause denial of service via crafted HTTP requests. The server mishandles errors triggered by the Expect request header and dereferences a NULL pointer. Network access to an enabled web server is required; Siemens does not state whether the resulting interruption is a crash, hang, or reboot.

CVSS severity5.9
Medium
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in web servers across Siemens SIMATIC products allows remote attackers to cause denial of service via crafted HTTP requests. The server mishandles errors triggered by the Expect request header and dereferences a NULL pointer. Network access to an enabled web server is required; Siemens does not state whether the resulting interruption is a crash, hang, or reboot.

The record

CVE
CVE-2023-30756
Published
Sep 10, 2024
Updated
Sep 10, 2024
Vendor
Siemens
Product
SIMATIC WinCC Runtime Advanced
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 10, 2024CVE publishedPublication date reported by the CVE source.
  2. Sep 10, 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=All versions

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIMATIC WinCC Runtime Advancedversion=All versions
Siemens · SIMATIC CP 1243-1version=0 <V3.5.20
Siemens · TIM 1531 IRCversion=0 <V2.4.8
Siemens · SIMATIC CP 1242-7 V2version=0 <V3.5.20
Siemens · SIPLUS TIM 1531 IRCversion=0 <V2.4.8
Siemens · SIMATIC CP 1243-8 IRCversion=0 <V3.5.20
Siemens · SIMATIC IPC DiagMonitorversion=All versions
Siemens · SIMATIC IPC DiagBaseversion=0 <*
Siemens · SIMATIC HMI Comfort Panelsversion=All versions
Siemens · SIMATIC CP 1243-1 IECversion=0 <V3.5.20
Siemens · SIMATIC CP 1243-7 LTEversion=0 <V3.5.20
Siemens · SIMATIC CP 1243-1 DNP3version=0 <V3.5.20

Published CVSS scores

5.9Siemens AGCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
8.2Siemens AGCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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-476NULL Pointer Dereference
T1499.004Application or System Exploitation

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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