RT-Labs P-Net: Out-of-bounds write when parsing AR Vendor Block requests
Summary
RT-Labs P-Net, a PROFINET device stack used in embedded industrial devices, contains an out-of-bounds write when parsing AR Vendor Block requests. Only builds with the compile option PNET_OPTION_AR_VENDOR_BLOCKS enabled are affected, and this option is disabled by default. A crafted Connect request sent over the network, without authentication or user interaction, can crash the device (denial of service) and potentially allow arbitrary code execution.
Affected
- RT-Labs P-Net versions 0 to before 1.0.3
- Only builds with PNET_OPTION_AR_VENDOR_BLOCKS enabled (disabled by default)
Fixed in
- Upgrade to P-Net 1.0.3 or later (per the CNA record; the 1.0.3 changelog was not verified)
Workaround
Unknown. No vendor workaround has been published.
- Check whether the firmware was built with PNET_OPTION_AR_VENDOR_BLOCKS enabled. Turning it off requires a rebuild.
- Keep PROFINET and industrial control traffic on isolated segments and allow RPC traffic only from known engineering stations and controllers.
Exploitation
- No evidence of exploitation in the wild found.
- One aggregator lists the CVE as not in CISA KEV.
- No public proof of concept found; this does not prove that none exists.
Our recommendation
- Ask device and machine vendors whether their firmware embeds P-Net, which version is used, and whether PNET_OPTION_AR_VENDOR_BLOCKS is enabled.
- Obtain firmware updates that include P-Net 1.0.3 or later and apply them.
- Restrict PROFINET and RPC traffic to engineering stations and controllers, and monitor the segment for unexpected Connect requests.
- Priority: medium to high where PROFINET devices are reachable from enterprise networks; lower where they sit on isolated control segments with vendor-confirmed builds.
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
- P-Net releases (GitHub) github.com
- CVE-2026-111732 (Strix) www.strix.ai
- CVE-2026-111732 (threatint) cve.threatint.com
- CVE-2025-32404 analysis (Safeguard) safeguard.sh
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, 00:27.
Original description (NVD)
P-Net before 1.0.3, when built with PNET_OPTION_AR_VENDOR_BLOCKS enabled, parses a data length from a field of the ARVendorBlock request that is not part of the block definition and uses it as the number of bytes to copy into a fixed-size buffer, without comparing it with the buffer size or the block length. A crafted Connect request causes an out-of-bounds write. This can lead to a crash (denial of service) or potentially arbitrary code execution. This option is disabled by default.
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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