RT-Labs P-Net: Denial of service via unreleased RPC sessions and AR
Summary
P-Net, a PROFINET IO stack for embedded industrial field devices, does not release the Application Relationship and RPC session when an RPC request with incorrect endianness is rejected. Repeated requests exhaust the available sessions, and the device stops answering new RPC requests, including Connect, until it is restarted. A remote unauthenticated attacker on the network can cause a denial of service, which can interrupt a production process.
Affected
- RT-Labs P-Net versions before 1.0.3 (per the CNA record; VulDB lists up to 1.0.2)
- Devices that ship with an affected P-Net version in their firmware
Fixed in
- P-Net 1.0.3 or later (per the CNA record and VulDB)
- Unknown: the specific 1.0.3 changelog entry for this issue
Workaround
- Unknown. No vendor-documented workaround was found.
Exploitation
- No evidence of in-the-wild exploitation or public proof of concept was found.
- The EPSS score is 0.41 % (percentile 36).
- The VulDB "0-Day" label describes disclosure timing, not exploitation.
Our recommendation
- Inventory PROFINET devices and their firmware versions.
- Ask device vendors whether their firmware includes P-Net 1.0.3 or later, and apply updates.
- Confirm that PROFINET field devices sit in a segregated OT network and block RPC/UDP access from untrusted segments.
- Prepare a restart procedure for affected devices, since a restart is the only recovery described.
- Monitor for repeated RPC requests and unresponsive devices.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- RT-Labs advisory RRTL-261019-01 rt-labs.com
- VulDB entry 428599 vuldb.com
- ThreatInt CVE record cve.threatint.com
- Strix CVE record www.strix.ai
- P-Net GitHub releases github.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 23:36.
Original description (NVD)
P-Net before 1.0.3 does not release the Application Relationship (AR) and the RPC session when an RPC request is rejected because its data representation has incorrect endianness. The session and its AR remain allocated, so repeated requests exhaust the available sessions. Once they are exhausted the device no longer answers new RPC requests, including Connect, until it is restarted. A remote unauthenticated attacker can use this to cause a denial of service.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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