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Full vulnerability report · 2025
CVE-2025-41691High confidence

CODESYS Control DoS via Unauthenticated NULL Pointer Dereference

CODESYS · Control RTE (SL)

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

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 0.55% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs CODESYS Control RTE (SL) and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Direct vendor intelligence

Authoritative 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.

1 current
3ADR011524 · CSAF 2.0 · revision 1 · finalABB Product Security Incident Response Team (PSIRT)CVE-2025-41691
1 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • ABB AC500 V3 <3.9.0
Summary
A vulnerability in the runtime system's CmpDevice component allows unauthenticated attackers to cause a denial-of-service (DoS) via specially crafted communication requests. The issue is triggered by a NULL pointer dereference and also affects systems when outdated clients attempt to log in.
Remediation
The problem is corrected in the following product versions: - AC500 V3 firmware version 3.9.0 ABB recommends that customers apply the update at earliest convenience. This firmware version is released for all AC500 V3 PLC types and available from Automation Builder 2.9.0. Automation Builder 2.9.0 is available for download from the related download site. https://www.abb.com/global/en/areas/motion/digital-tools/automation-builder/software-download
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2025-23490

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

An unauthenticated remote attacker may trigger a NULL pointer dereference in the affected CODESYS Control runtime systems by sending specially crafted communication requests, potentially leading to a denial-of-service (DoS) condition.

What

An unauthenticated remote attacker may trigger a NULL pointer dereference in the affected CODESYS Control runtime systems by sending specially crafted communication requests, potentially leading to a denial-of-service (DoS) condition.

Why

The product dereferences a pointer that it expects to be valid but is NULL.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

An unauthenticated remote attacker may trigger a NULL pointer dereference in the affected CODESYS Control runtime systems by sending specially crafted communication requests, potentially leading to a denial-of-service (DoS) condition.

Why

The product dereferences a pointer that it expects to be valid but is NULL.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

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
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

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 → NULL Pointer Dereference → cause the confidentiality, integrity or availability impact described by the vendor
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-476 ↗

CWE-476: NULL Pointer Dereference. The product dereferences a pointer that it expects to be valid but is NULL.

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

Common 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.
NetworkUnauthenticatedCWE-476
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2025-1705CODESYS: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in CODESYS ausnutzen, um einen Denial-of-Service-Zustand auszulösen, Daten zu manipulieren und vertrauliche Informationen preiszugeben.

Official advisory ↗
Canadian Centre for Cyber Security · English · AV26-163[Control systems] ABB security advisory (AV26-163)

On February 24, 2026, ABB published security advisories to address vulnerabilities in the following products:

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20250806Security Bulletin 06 Aug 2025

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 06 Aug 2025, published on 6 August 2025. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
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.
Patch available
Affected
ABB AC500 V3 <3.9.0
Fixed
ABB AC500 V3 3.9.0
Action
The problem is corrected in the following product versions: - AC500 V3 firmware version 3.9.0 ABB recommends that customers apply the update at earliest convenience. This firmware version is released for all AC500 V3 PLC types and available from Automation Builder 2.9.0. Automation Builder 2.9.0 is available for download from the related download site. https://www.abb.com/global/en/areas/motion/digital-tools/automation-builder/software-download
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 4 Aug 2025 · Last source change 4 Aug 2025, 16:32 UTC · CWE-476 · NULL Pointer Dereference

CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-23490
Product sourceVendor CSAF · ABB Product Security Incident Response Team (PSIRT)
Remediation sourceVendor CSAF · ABB Product Security Incident Response Team (PSIRT)
CWE sourceCNA
NVD statusNVD not scheduled

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    3.5.21.10 < 3.5.21.20; 4.16.0.0 < 4.17.0.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    3.5.21.10 < 3.5.21.20; 4.16.0.0 < 4.17.0.0 · Fixed: The problem is corrected in the following product versions: - AC500 V3 firmware version 3.9.0 ABB recommends that customers apply the update at earliest convenience. This firmware version is released for all AC500 V3 PLC types and available from Automation Builder 2.9.0. Automation Builder 2.9.0 is available for download from the related download site. https://www.abb.com/global/en/areas/motion/digital-tools/automation-builder/software-download
    ABB Product Security Incident Response Team (PSIRT) ↗
  2. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    ABB Product Security Incident Response Team (PSIRT) ↗
  3. Vendor guidanceAuthoritative vendor guidance changed: added remediation: search.abb.com/Download.aspx?DocumentID=3ADR011524&LanguageCode=en&DocumentPartId=&Action=Launch; removed remediation: nvd.nist.gov/CVE-2025-41691.
    Before
    remediation: nvd.nist.gov/CVE-2025-41691
    After
    remediation: search.abb.com/Download.aspx?DocumentID=3ADR011524&LanguageCode=en&DocumentPartId=&Action=Launch
    ABB Product Security Incident Response Team (PSIRT) ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2025-23490↗ABB Product Security Incident Response Team (PSIRT) security advisory↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
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.
Free version - for non-commercial use only.CVE-2025-41691 · cve.blacktree.nl