CVE-2026-111734 in P-Net
Summary
by MITRE • 10/29/2026
P-Net before 1.0.3 does not validate the length of a received Ethernet frame in pf_eth_recv() before reading the EtherType, any VLAN tags and the PROFINET FrameID. The VLAN tag loop had no upper bound, so a truncated frame, or a frame consisting only of VLAN tags, makes the function read past the end of the receive buffer. This can cause a crash (denial of service) or disclose memory content.
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Analysis
by VulDB Data Team • 10/29/2026
The vulnerability in P-Net versions prior to 1.0.3 represents a critical input validation failure within the network stack implementation, specifically located in the pf_eth_recv function responsible for processing incoming Ethernet frames. This flaw stems from an absence of boundary checks when parsing protocol headers, allowing malformed or truncated packets to trigger out-of-bounds memory access. In industrial automation environments where P-Net is deployed as a real-time communication protocol over standard Ethernet infrastructure, such vulnerabilities pose significant risks to system availability and data integrity due to the sensitive nature of operational technology networks.
The technical root cause lies in the logic used to parse VLAN tags within received frames. The implementation employs an unbounded loop to iterate through potential 802.1Q VLAN headers embedded in the Ethernet frame header. Standard Ethernet frames contain a fixed-size EtherType field immediately following the destination and source MAC addresses, but P-Net implementations must also handle optional VLAN tagging which can stack multiple tags before reaching higher-layer protocol identifiers like PROFINET FrameID. The code fails to verify that sufficient bytes remain in the receive buffer before attempting to read these fields. Consequently, if an attacker sends a truncated frame or one composed entirely of VLAN tag headers without subsequent payload data, the parser continues reading beyond the allocated memory region associated with the packet buffer.
This out-of-bounds read operation leads directly to two primary adverse outcomes depending on system state and compiler optimizations. First, accessing invalid memory addresses typically triggers segmentation faults or general protection violations within the operating kernel or network driver context, resulting in an immediate crash of the P-Net stack or potentially the entire host device. This constitutes a denial-of-service condition that can disrupt industrial processes relying on continuous real-time communication. Second, if the out-of-bounds read occurs into memory regions containing sensitive data such as cryptographic keys, session tokens, or other process information, it may lead to unauthorized disclosure of internal system state through error messages, log dumps, or side-channel effects observable by a remote attacker capable of injecting crafted packets.
From an industry standard perspective, this vulnerability aligns with CWE-125 Out-of-bounds Read and CWE-20 Improper Input Validation as defined in the Common Weakness Enumeration database. The attack vector allows for remote exploitation without authentication if the P-Net interface is exposed to untrusted networks, mapping closely to MITRE ATT&CK technique T1498 Network Denial of Service under Impact categories related to Availability and Confidentiality. Industrial control systems often assume physical isolation or trusted network segments, making such protocol-level flaws particularly dangerous as they bypass perimeter defenses that do not inspect deep packet contents for malformed structures.
Mitigation strategies must prioritize immediate patching to version 1.0.3 or later where the pf_eth_recv function includes proper length checks before accessing EtherType and VLAN tag fields. Network administrators should implement strict ingress filtering rules at network boundaries to drop packets with suspiciously high numbers of VLAN tags or truncated Ethernet frames, effectively neutralizing the exploit vector until patches are applied. Additionally, deploying intrusion detection systems capable of identifying malformed protocol structures can provide an additional layer of defense against automated scanning and exploitation attempts targeting this specific implementation flaw in industrial automation infrastructure.