CVE-2026-111733 in P-Net
Summary
by MITRE • 10/29/2026
P-Net before 1.0.3 dereferences a NULL AR pointer when handling an implicit read request without a valid target AR UUID for a record index that requires an AR (AR specific indices 0xE000-0xEFFF, and the expected identification data of a slot or subslot). A remote unauthenticated attacker can send such a request to crash the device (denial of service).
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Analysis
by VulDB Data Team • 10/29/2026
The vulnerability identified in P-Net versions prior to 1.0.3 represents a critical memory management flaw rooted in improper input validation and null pointer dereference logic within the protocol stack's handling of implicit read requests. Specifically, the defect occurs when the system processes an implicit read operation targeting record indices that necessitate Access Region (AR) specific data, namely those falling within the range 0xE000 to 0xEFFF. These indices are designed to retrieve identification data for slots or subslots in industrial networking environments governed by P-Net standards. The core technical failure lies in the application's inability to verify whether a valid target AR Universally Unique Identifier (UUID) is present and correctly resolved before attempting to access memory structures associated with that AR. When an unauthenticated remote attacker crafts a malicious packet containing such a request without providing or referencing a valid AR UUID, the internal pointer resolution mechanism fails to locate the corresponding object in memory. Instead of returning an appropriate error code or gracefully handling the missing reference, the software proceeds to dereference a NULL pointer, leading directly to a segmentation fault and subsequent application crash.
From a security architecture perspective, this flaw is classified under CWE-476, which denotes a NULL Pointer Dereference vulnerability. This type of defect typically arises when developers assume that certain preconditions are always met without performing explicit checks for null values before memory access operations. In the context of industrial control systems and fieldbus networks where P-Net operates, such assumptions can be particularly dangerous due to the real-time nature of these protocols and the limited resources available on embedded devices. The lack of authentication requirements further exacerbates the severity, as it allows any network participant with connectivity to exploit this condition without needing valid credentials or prior handshake establishment. This aligns with ATT&CK technique T1498, Network Denial of Service, specifically sub-technique 002, which involves exploiting protocol vulnerabilities to disrupt service availability rather than overwhelming bandwidth through volumetric attacks.
The operational impact of this vulnerability is a complete denial of service against the affected P-Net device or controller. Since industrial automation systems often rely on continuous and deterministic communication cycles, an unexpected crash can halt production lines, disable safety monitoring functions, or cause data loss in connected SCADA systems. The attacker does not need to inject malicious code or achieve remote execution; simply sending a single malformed packet is sufficient to trigger the fault condition. This simplicity makes it highly exploitable by automated scanning tools or opportunistic attackers targeting exposed industrial network segments. Furthermore, because the vulnerability occurs during standard protocol operations like implicit reads, which are common in normal device polling scenarios, distinguishing malicious traffic from legitimate background noise can be challenging for intrusion detection systems that do not perform deep packet inspection with specific knowledge of P-Net internal state machines.
Mitigation strategies must focus on both immediate patching and long-term architectural hardening. The primary remediation is to upgrade the affected software to version 1.0.3 or later, where developers have implemented proper null checks and error handling routines for AR pointer resolution during implicit read operations. For environments where immediate upgrading is not feasible due to operational constraints, network segmentation should be enforced to restrict access to P-Net devices from untrusted networks. Implementing strict firewall rules that filter out malformed packets based on known vulnerability signatures can also provide a layer of defense-in-depth. Additionally, developers should adopt secure coding practices that mandate validation of all external inputs and pointer dereferences against null values before execution, ensuring resilience against similar memory corruption vulnerabilities in future releases.