CVE-2026-124758RT-Labs P-Net integer underflow
CVE-2026-124758 is a integer underflow in RT-Labs P-Net, rated low (2.3 on CVSS 4.0).
Why this priority: Low severity, with no exploitation signal.
Published · Updated · NVD status: Deferred
What it is
A subtraction wraps below zero and produces a huge value used as a size or index.
How it is reached
An attacker can exploit it from the same local network segment, without an account, and nobody has to click anything. Success also depends on conditions the attacker does not fully control.
What an attacker gains
The direct impact is limited: partial access to data or a partial outage. In practice, this kind of flaw lets an attacker crash the process, read memory, or in the worst case run code.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- Upgrade RT-Labs P-Net to 1.0.4 or later.
- Segment the networks that can reach it.
Description from NVD
P-Net before 1.0.4 does not check the record data length of an IODWrite request to a non-user record index against the size of the record block header. The 32-bit length is reduced by the header size before it is passed to the record handlers, so a length smaller than the header underflows and the handlers receive a data length of about 65530. The fixed-size reads of the I&M and PDPort handlers can then read past the end of the session buffer. The result of the write is discarded. The attacker must have an established Application Relationship or be able to send in the context of one, and requires ADJACENT network access.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Native code: operating systems, browsers and firmware. The flaw sits wherever native code reads untrusted data.
- Network appliances and media or file parsers. The flaw sits wherever native code reads untrusted data.
Trust boundaries in play
- Local network segment. The attacker must share a network segment with the target.
- Wherever native code reads untrusted data. An attacker who crosses it can crash the process, read memory, or in the worst case run code.
Questions to answer about your own systems
- Where does RT-Labs P-Net run in your systems, and at which version?
- Which network segments can reach them?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.