# CVE-2026-124762: RPC reject, fault and cancel PDUs abort an Application Relationship

Status: published. Published: 2026-11-13. Updated: 2026-11-13.

P-Net before 1.0.4 finds the RPC session of a received PDU by its activity UUID only, and a reject, fault or cancel PDU for the session aborts the Application Relationship, without checking that the PDU is the answer to a call of the device or where it comes from. A host with ADJACENT network access that has observed the activity UUID of the connection, which is sent in clear in every RPC request, can abort the Application Relationship with one PDU. It also allocates a session for an unknown activity UUID and changes the address stored for an existing session.

## Remediation

- fix: Upgrade to P-Net 1.0.4 or later, which only handles a reject or fault as the answer to a call of the device and ignores a cancel. It reduces the risk but does not remove it, see Remaining Risk. (source: CNA: rt-labs)
- workaround: Isolate the network of the device from untrusted hosts, for example by a firewall or a separate network,. The remaining risk is that a host that has observed the activity UUID and the sequence number of a pending call of the device can still send a forged reject or fault. (source: CNA: rt-labs)

## Affected products and versions

- RT-Labs / P-Net: ≥ 0; < 1.0.4 (affected, semver); ≥ 1.0.4; < * (affected, semver). Source: CNA: rt-labs

## Severity and prioritization

- CVSS 4.0: 6 (medium); CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N; source: CNA: rt-labs

- CVSS 4.0: 6 (medium); CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: 4b71179a-3b92-4a9d-b9fc-af8b8ed579ee

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-346

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://rt-labs.com/wp-content/uploads/2026/11/RRTL-261109-01.pdf (CNA: rt-labs)

- https://rt-labs.com/wp-content/uploads/2026/11/RRTL-261109-01.pdf (4b71179a-3b92-4a9d-b9fc-af8b8ed579ee)

## Provenance

- CNA: rt-labs: https://www.cve.org/CVERecord?id=CVE-2026-124762; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-124762; retrieved 2026-11-13; source updated 2026-11-13

Revision: bdc044900ba5d41beca003d78a41a6725a81687ed4d46b6192848fe698ff1e5e

Canonical: https://y2.dev/cve/CVE-2026-124762

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