# CVE-2026-127123: Fragment with another data representation releases an Application Relationship

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

P-Net before 1.0.4 releases the Application Relationship of an RPC session, without the abort procedure, when a fragment of a request has another data representation (endianness) than the first fragment of the call. The application is not told that the Application Relationship is gone, the cyclic data stops, and the resources of the Application Relationship are left referencing a cleared structure. Another host can then connect in its place. 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 do this with one PDU.

## Remediation

- fix: Upgrade to P-Net 1.0.4 or later. (source: CNA: rt-labs)

## Affected products and versions

- RT-Labs / P-Net: ≥ 0; < 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:L/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:L/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-404

## 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-2026-127123; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-127123; retrieved 2026-11-13; source updated 2026-11-13

Revision: c0e19111c0ec496f09708a363a4e1dfde3f8e74ad08328fb52f5daecc17e3a8f

Canonical: https://y2.dev/cve/CVE-2026-127123

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