VulnerabilityPublished 4 Aug 2025

CVE-2025-41691: CODESYS Control RTE (SL) · NULL Pointer Dereference

Affects CODESYS Control RTE (SL)Source CVE Database V5

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Not known to be exploited · CVSS 7.5 High.

Data as of 14 Nov 2026, 20:43 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.6% chance of exploitation in 30 days – higher than 51% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Aug 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 14 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
CODESYS Control RTE (SL)	Affected =3.5.21.10	Fixed in–

AI-suggested

Immediate identification and inventory of all CODESYS Control RTE (SL) version 3.5.21.10 deployments within the organization.
Apply vendor patches or updates as soon as they become available; monitor CODESYS advisories for official fixes.
Implement network segmentation to isolate industrial control systems from general IT networks and restrict access to CODESYS Control RTE devices to trusted management networks only.
Deploy intrusion detection/prevention systems (IDS/IPS) with signatures or anomaly detection capabilities tailored to detect malformed or suspicious communication requests targeting CODESYS protocols.
Employ strict firewall rules to limit inbound traffic to only necessary sources and ports used by CODESYS Control RTE.
Conduct regular security assessments and penetration tests focusing on industrial control systems to identify potential exploitation attempts.
Establish robust incident response plans specific to OT environments to quickly respond to DoS events affecting control systems.
Train operational staff to recognize signs of system instability or crashes that may indicate exploitation attempts.
Consider temporary compensating controls such as disabling unnecessary communication interfaces or protocols on affected devices until patches are applied.

Description

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.

Impact

For European organizations, especially those operating in industrial automation, manufacturing, energy, and critical infrastructure sectors, this vulnerability poses a significant risk. Exploitation can lead to denial-of-service conditions on control systems, potentially halting production lines, disrupting energy distribution, or impairing critical infrastructure operations. Such disruptions can cause financial losses, safety hazards, and regulatory compliance issues under frameworks like NIS2 and GDPR if service availability impacts data processing or safety. The fact that exploitation requires no authentication and can be performed remotely increases the threat level, as attackers do not need insider access. Although no data confidentiality or integrity is directly compromised, the availability impact alone can have cascading effects in interconnected industrial environments. European organizations relying on CODESYS Control RTE should consider this vulnerability a critical operational risk, particularly in sectors where uptime and system reliability are paramount.

CWE-476NULL Pointer Dereference (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #13OWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
The product dereferences a pointer that it expects to be valid but is NULL.
Implementation
For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
Requirements
Select a programming language that is not susceptible to these issues.
Implementation
Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
OWASP ASVS 4.0.3
V11.1.7 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

certvde.com/de/advisories/VDE-2025-070 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Aug 2025, 08:32 UTC

WeaknessesCWE-476

Technical details

References

Community reviews

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