CVE-2026-115794 in P-Net
Summary
by MITRE • 10/29/2026
P-Net before 1.0.3 passes the application alarm callback a data length derived from the variable part length field of a received RTA alarm frame without checking it against the length of the received frame. A short frame can make the callback receive a length of up to 65507 bytes. An application that copies the reported number of bytes reads past the end of the receive buffer. The attacker must have established an Application Relationship and requires ADJACENT network access. Applications that do not use the alarm data are not affected.
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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 input validation failure within the protocol's handling of Real-Time Alarm (RTA) frames, specifically concerning application alarm callbacks. The core technical flaw lies in the absence of bounds checking when processing the variable part length field contained within an incoming RTA alarm frame. Instead of validating that this declared length corresponds to or is less than the actual size of the received data payload, the software directly trusts and passes this value to the associated application callback function. This lack of verification allows a malicious actor who has established an Application Relationship with the target system to manipulate the length field in crafted network packets. By sending a frame where the declared variable part length significantly exceeds the actual amount of data transmitted, typically by setting it to a high value such as 65507 bytes while providing only minimal or no payload data, the attacker triggers an out-of-bounds read condition within the application layer software that consumes this callback.
From a technical perspective, this flaw is classified under CWE-20 Improper Input Validation and CWE-126 Buffer Over-read. When the application receives the alarm callback with the inflated length parameter, it proceeds to copy or process data based on this untrusted value. Since the actual buffer containing the received frame does not contain that many bytes of valid data, the memory access operations extend beyond the allocated boundaries of the receive buffer. This results in reading arbitrary memory contents located immediately after the buffer end. Depending on how the application handles these invalid reads and subsequent processing steps, this can lead to information disclosure where sensitive internal state or cryptographic keys are leaked into network traffic or logs, or it may cause a denial of service if the read operation triggers an access violation exception that crashes the process. The severity is compounded by the fact that P-Net is often used in industrial automation environments where system stability and data integrity are paramount.
The operational impact of this vulnerability is contingent upon specific network conditions and application configurations. An attacker must possess ADJACENT network access, meaning they need to be on the same local area network segment as the vulnerable device or have a direct Layer 2 connection capable of injecting raw Ethernet frames into the P-Net traffic stream. Furthermore, exploitation requires that an Application Relationship has already been established between the attacker's endpoint and the target system, which may involve authentication or handshake procedures depending on the specific implementation details of the P-Net stack in use. It is important to note that applications configured not to utilize alarm data are inherently immune to this specific attack vector, as they do invoke the vulnerable callback function. However, for systems relying on real-time alarms for safety monitoring or process control, successful exploitation could disrupt critical operations by causing application crashes or corrupting memory states through subsequent writes if the vulnerability is chained with other flaws like buffer overflows triggered by similar length mismanagement.
Mitigation strategies primarily involve upgrading to P-Net version 1.0.3 or later, where this input validation logic has been corrected to ensure that the declared variable part length is strictly checked against the actual received frame size before being passed to any application callback. In environments where immediate patching is not feasible due to operational constraints, network segmentation should be enforced to restrict ADJACENT access from untrusted or potentially compromised hosts on the industrial control network. Additionally, implementing deep packet inspection at the network perimeter can help detect anomalous P-Net frames with suspiciously large length fields relative to their payload size, although this requires specific signature development for RTA frame structures. Security architects should also review application code that consumes alarm data to ensure defensive programming practices are employed, such as verifying buffer sizes before copying operations and handling potential exceptions gracefully to prevent crashes from malformed inputs regardless of the underlying protocol stack vulnerabilities. This incident highlights the importance of strict input validation in industrial protocols where trust boundaries between network segments must be rigorously maintained to protect against both accidental errors and deliberate exploitation by adjacent attackers.