CVE-2023-48795Public exploitNetwork attack vector

SSH security downgrade via sequence-number manipulation

Published Dec 18, 2023 · Updated Jul 14, 2026

Improper integrity validation in Siemens industrial SSH endpoints allows man-in-the-middle attackers to remove handshake packets. The Binary Packet Protocol carries sequence numbers across the SSH handshake, letting injected unauthenticated packets advance them before encryption so selected extension-negotiation packets can be truncated without detection. Exploitation requires active network interception and negotiation of ChaCha20-Poly1305 or CBC with Encrypt-then-MAC; the bounded result is a connection with security features downgraded or disabled.

CVSS severity5.9
Medium
EPSS probability93.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper integrity validation in Siemens industrial SSH endpoints allows man-in-the-middle attackers to remove handshake packets. The Binary Packet Protocol carries sequence numbers across the SSH handshake, letting injected unauthenticated packets advance them before encryption so selected extension-negotiation packets can be truncated without detection. Exploitation requires active network interception and negotiation of ChaCha20-Poly1305 or CBC with Encrypt-then-MAC; the bounded result is a connection with security features downgraded or disabled.

The record

CVE
CVE-2023-48795
Published
Dec 18, 2023
Updated
Jul 14, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-354, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 18, 2023CVE publishedPublication date reported by the CVE source.
  2. Jul 14, 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=V3.1.5 <*

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*
Siemens · RUGGEDCOM APE1808version=0 <*
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.5 <*
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*

Published CVSS scores

5.9CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A: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 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 exploitPublished

Weakness, pattern, technique

CWE-354Improper Validation of Integrity Check Value
T1557Adversary-in-the-Middle

Public exploit references

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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