Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.60% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2024
CVE-2023-51440High confidence
Siemens SIMATIC CP 343-1 — Improper Verification of Source of a Communication Channel
Siemens · SIMATIC CP 343-1
Official source article: Siemens SSA-516818 ↗. Check the applicable product and release in the original source.
7.5HighCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productHigh technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 4 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Apply the linked authoritative mitigation while planning the permanent fix.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Siemens SIMATIC CP 343-1 and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 4 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Siemens ProductCERT: 4 affected or under-investigation product states without a fixed product state in the same current advisory
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
SSA-516818 · CSAF 2.0 · revision 1 · finalSiemens ProductCERTSSA-516818: TCP Sequence Number Validation Vulnerability in the TCP/IP Stack of CP343-1 Devices
The vendor explicitly identifies these products as affected by this CVE.
- SIMATIC CP 343-1 (6GK7343-1EX30-0XE0)
- SIMATIC CP 343-1 Lean (6GK7343-1CX10-0XE0)
- SIPLUS NET CP 343-1 (6AG1343-1EX30-7XE0)
- SIPLUS NET CP 343-1 Lean (6AG1343-1CX10-2XE0)
- Summary
- Affected products incorrectly validate TCP sequence numbers. This could allow an unauthenticated remote attacker to create a denial of service condition by injecting spoofed TCP RST packets.
- Remediation
- Apply network segmentation and Defense-in-Depth practices to reduce likelihood of a threat actor to be able to reach a potentially vulnerable device
High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 4 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
A vulnerability has been identified in SIMATIC CP 343-1 (6GK7343-1EX30-0XE0) (All versions), SIMATIC CP 343-1 Lean (6GK7343-1CX10-0XE0) (All versions), SIPLUS NET CP 343-1 (6AG1343-1EX30-7XE0) (All versions), SIPLUS NET CP 343-1 Lean (6AG1343-1CX10-2XE0) (All versions). Affected products incorrectly validate TCP sequence numbers. This could allow an unauthenticated remote attacker to create a denial of service condition by injecting spoofed TCP RST packets.
What
A vulnerability has been identified in SIMATIC CP 343-1 (6GK7343-1EX30-0XE0) (All versions), SIMATIC CP 343-1 Lean (6GK7343-1CX10-0XE0) (All versions), SIPLUS NET CP 343-1 (6AG1343-1EX30-7XE0) (All versions), SIPLUS NET CP 343-1 Lean (6AG1343-1CX10-2XE0) (All versions). Affected products incorrectly validate TCP sequence numbers. This could allow an unauthenticated remote attacker to create a denial of service condition by injecting spoofed TCP RST packets.
Why
The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
What
A vulnerability has been identified in SIMATIC CP 343-1 (6GK7343-1EX30-0XE0) (All versions), SIMATIC CP 343-1 Lean (6GK7343-1CX10-0XE0) (All versions), SIPLUS NET CP 343-1 (6AG1343-1EX30-7XE0) (All versions), SIPLUS NET CP 343-1 Lean (6AG1343-1CX10-2XE0) (All versions). Affected products incorrectly validate TCP sequence numbers. This could allow an unauthenticated remote attacker to create a denial of service condition by injecting spoofed TCP RST packets.
Why
The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Improper Verification of Source of a Communication Channel → disrupt the affected service
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-940 ↗
CWE-940: Improper Verification of Source of a Communication Channel. The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:T/RC:CCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix availability varies by product
- Affected
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- Apply network segmentation and Defense-in-Depth practices to reduce likelihood of a threat actor to be able to reach a potentially vulnerable device
04
Evidence and provenance
Published 13 Feb 2024 · Last source change 2 Aug 2024, 22:32 UTC · CWE-940 · Improper Verification of Source of a Communication Channel
CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2023-56160
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceCNA
NVD statusNVD enriched
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.