P-Net before 1.0.4 does not check the number of MCR request blocks in a Connect request against the number of multicast communication relations that an Application Relationship has room for (PNET_MAX_MC_CR, 1 by default). Each further block is written past the end of the array, into the rest of the Application Relationship and, with more blocks, into the following one. The written data comes from the request. No established Application Relationship is needed, and the attacker requires ADJACENT network access. Builds with PNET_OPTION_MC_CR disabled are not affected.
"}],"value":"P-Net before 1.0.4 does not check the number of MCR request blocks in a Connect request against the number of multicast communication relations that an Application Relationship has room for (PNET_MAX_MC_CR, 1 by default). Each further block is written past the end of the array, into the rest of the Application Relationship and, with more blocks, into the following one. The written data comes from the request. No established Application Relationship is needed, and the attacker requires ADJACENT network access. Builds with PNET_OPTION_MC_CR disabled are not affected."}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"ADJACENT","baseScore":7.2,"baseSeverity":"HIGH","exploitMaturity":"NOT_DEFINED","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-787","description":"CWE-787 Out-of-bounds Write","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-11-13T13:24:43.878Z","orgId":"4b71179a-3b92-4a9d-b9fc-af8b8ed579ee","shortName":"rt-labs"},"references":[{"name":"Cybersecurity advisory for P-Net","url":"https://rt-labs.com/wp-content/uploads/2026/11/RRTL-261109-01.pdf"}],"solutions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Upgrade to P-Net 1.0.4 or later.
"}],"value":"Upgrade to P-Net 1.0.4 or later."}],"source":{"discovery":"INTERNAL"},"title":"Out-of-bounds write with too many MCR blocks in a Connect request","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Build P-Net with PNET_OPTION_MC_CR disabled. Multicast communication relations are not supported by P-Net, and a Connect request with MCR blocks is then rejected.
"}],"value":"Build P-Net with PNET_OPTION_MC_CR disabled. Multicast communication relations are not supported by P-Net, and a Connect request with MCR blocks is then rejected."}]}},"cveMetadata":{"assignerOrgId":"4b71179a-3b92-4a9d-b9fc-af8b8ed579ee","assignerShortName":"rt-labs","cveId":"CVE-2026-127122","datePublished":"2026-11-13T13:24:43.878Z","dateReserved":"2026-11-12T15:30:49.638Z","dateUpdated":"2026-11-13T20:06:09.052Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-11-13 14:17:54","lastModifiedDate":"2026-11-13 20:18:50","problem_types":["CWE-787","CWE-787 CWE-787 Out-of-bounds Write"],"metrics":{"cvssMetricV40":[{"source":"4b71179a-3b92-4a9d-b9fc-af8b8ed579ee","type":"Secondary","cvssData":{"version":"4.0","vectorString":"CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/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","baseScore":7.2,"baseSeverity":"HIGH","attackVector":"ADJACENT","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-11-13T19:54:47.653840Z","id":"CVE-2026-127122","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"127122","Ordinal":"1","Title":"Out-of-bounds write with too many MCR blocks in a Connect reques","CVE":"CVE-2026-127122","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"127122","Ordinal":"1","NoteData":"P-Net before 1.0.4 does not check the number of MCR request blocks in a Connect request against the number of multicast communication relations that an Application Relationship has room for (PNET_MAX_MC_CR, 1 by default). Each further block is written past the end of the array, into the rest of the Application Relationship and, with more blocks, into the following one. The written data comes from the request. No established Application Relationship is needed, and the attacker requires ADJACENT network access. Builds with PNET_OPTION_MC_CR disabled are not affected.","Type":"Description","Title":"Out-of-bounds write with too many MCR blocks in a Connect reques"}]}}}