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01 Record

CVE-2025-40820

Affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range. This could allow an unauthenticated remote attacker e.g. to

HighPUBLISHEDCNA: siemens
CNA base score8.7 CVSS v4.0CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

02 Description

Affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range. This could allow an unauthenticated remote attacker e.g. to

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.49% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 41.8% of scored records. A rank, not a probability.
NVD base score
8.7 (CVSS v4.0), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD analysis status
Deferred. NVD last modified this record on 2026-10-07.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2025-12-09 10:44Z10 MO AGO
Last updated
2025-12-09 15:55Z10 MO AGO
Reserved
2025-04-16
Assigning CNA
siemens
Record state
PUBLISHED
Severity
High (CVSS 8.7)
CNA CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weaknesses
  • CWE-940Improper Verification of Source of a Communication ChannelBase
Data version
5.2
Document digest
33402dd838e515b17325fc13c2f856d61e7f3ca376dbfc66979691dffc40958a

05 Affected products

VendorProductVersionsPlatforms
SiemensSIDOOR ATD430W0 to < *—
SiemensSIDOOR ATE530G COATED0 to < *—
SiemensSIDOOR ATE530S COATED0 to < *—
SiemensSIMATIC CFU DIQ0 to < V2.0.0—
SiemensSIMATIC CFU PA0 to < V2.0.0—
SiemensSIMATIC ET 200MP IM 155-5 PN HFV4.2.0 to < *—
SiemensSIMATIC ET 200SP IM 155-6 PN HFV4.2.0 to < *—
SiemensSIMATIC ET 200SP IM 155-6 PN/2 HFV4.2.0 to < *—
SiemensSIMATIC ET 200SP IM 155-6 PN/3 HFV4.2.0 to < *—
SiemensSIMATIC PN/MF Coupler0 to < *—
SiemensSIMATIC PN/PN Coupler0 to < V6.0.0—
SiemensSIMATIC S7-1200 CPU 1211C DC/DC/DC0 to < V4.4.0—
SiemensSIMATIC S7-1200 CPU 1212C DC/DC/DC0 to < V4.4.0—
SiemensSIMATIC S7-1200 CPU 1214C DC/DC/DC0 to < V4.4.0—
SiemensSIMATIC S7-1200 CPU 1215C DC/DC/DC0 to < V4.4.0—
SiemensSIMATIC S7-1200 CPU 1217C DC/DC/DC0 to < V4.4.0—

85 further entries not shown. The complete list is in the raw JSON document.

06 References