{ "document": { "category": "opc_security_advisory", "csaf_version": "2.0", "distribution": { "tlp": { "label": "WHITE" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "The information provided in this disclosure is provided 'as is' without warranty of any kind. OPC Foundation disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall OPC Foundation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if OPC Foundation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply" } ], "publisher": { "category": "vendor", "name": "OPC Foundation", "namespace": "https://opcfoundation.org/security/csaf" }, "references": [ { "category": "self", "summary": "Advisory Source", "url": "https://github.com/OPCFoundation/SecurityAdvisories/tree/latest/csaf/2026/007" }, { "category": "external", "summary": "Mantis Issue", "url": "https://mantis.opcfoundation.org/view.php?id=10055" }, { "category": "external", "summary": "A Comprehensive Formal Security Analysis of OPC UA", "url": "https://eprint.iacr.org/2025/148" } ], "title": "Security Update for the OPC UA Specification", "tracking": { "current_release_date": "2026-09-15T00:00:00Z", "id": "OPC-2026-08-12-007", "initial_release_date": "2026-08-12T00:00:00Z", "revision_history": [ { "date": "2026-08-12T00:00:00Z", "number": "1.0.0", "summary": "Advisory created." }, { "date": "2026-09-15T00:00:00Z", "number": "1.0.1", "summary": "Added note on reporter/vendor disagreement." } ], "status": "release", "version": "1.0.1" } }, "product_tree": { "branches": [ { "category": "product_name", "name": "OPC UA Specification Part 4 - Services", "product": { "name": "OPC UA Specification Part 4 - Services <1.05.07", "product_id": "CSAFPID-04", "product_identification_helper": { "skus": [ "OPC 10000-4" ] } } } ] }, "vulnerabilities": [ { "acknowledgments": [ { "names": [ "Vincent Diemunsch" ], "organization": "ANSSI & Inria, France" }, { "names": [ "Lucca Hirschi" ], "organization": "Inria, France" }, { "names": [ "Steve Kremer" ], "organization": "Inria, France", "summary": "For discovering the issue using the ProVerif protocol analyzer, see eprint https://eprint.iacr.org/2025/148." } ], "cwe": { "id": "CWE-384", "name": "Session Fixation" }, "discovery_date": "2024-08-10T00:00:00Z", "ids": [ { "system_name": "GCVE", "text": "GCVE-105-2026-007" } ], "involvements": [ { "date": "2026-03-01T00:00:00Z", "party": "vendor", "status": "completed" } ], "notes": [ { "category": "other", "text": "The CVSS v3.1 score published here uses Scope:Unchanged (S:U): 5.9 (MEDIUM). The reporters assess Scope:Changed (S:C): 7.7 (HIGH). The disagreement concerns only the Scope metric. Reporter position: OPC UA secure-channel security (UA-SC/PKI) and session-and-user authentication are two distinct security authorities, each with its own certificate exchange and potentially implemented as separate components or processes; the attack chains a channel-layer key compromise into a session/user-identity compromise, crossing from one authority to the other, which the reporters consider a scope change. OPC Foundation position: the impacted resources (the Server's nodes, address space, and operations) are governed by exactly one security authority which evaluates the client certificate, the endpoint used, the user token, and other configured criteria as inputs to a single access-control decision applied on every operation (OPC 10000-18 4.4). The SecureChannel and PKI authenticate endpoints; they do not define or enforce which operations a subject may perform on Server resources. A separable implementation is not a separate security authority; CVSS Scope concerns authorization domains, not library, process, or code boundaries. The attack is a horizontal move to impersonate another user to the same Server and reach that Server's resources, which is the standard Scope:Unchanged pattern.", "title": "CVSS Scope Assessment (vendor / reporter disagreement)" } ], "references": [ { "summary": "CWE-384: Session Fixation", "url": "https://cwe.mitre.org/data/definitions/384.html" } ], "remediations": [ { "category": "vendor_fix", "details": "OPC UA Part 4 - Services 1.05.07 ยง6.1.8: Defines new calculations for user token signatures which prevent re-use of tokens.", "product_ids": [ "CSAFPID-04" ], "url": "https://reference.opcfoundation.org/Core/Part4/v105/docs/6.1.8" }, { "category": "mitigation", "details": "Following the OPC UA guidelines on managing private keys would reduce the likelihood that the prerequisites can be met. Specifically, protect Client private keys in hardware or a secure element where feasible and enforce strict decommissioning of retired keys; rotate private keys regularly; prefer SignAndEncrypt over Sign on exposed endpoints, which prevents the ActivateSession request from being observed on the network; and segment the network so that the traffic interception this attack requires is not available from general network positions.", "product_ids": [ "CSAFPID-04" ] } ], "scores": [ { "cvss_v3": { "baseScore": 5.9, "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N/E:P/RL:O/RC:C", "version": "3.1" }, "products": [ "CSAFPID-04" ] } ], "threats": [ { "category": "impact", "details": "An attacker could take control of a Session by intercepting and replaying an ActivateSession request with a compromised private key." }, { "category": "target_set", "details": "The attacker has access to the private key of a client with access to the target server and the SecureChannel is in sign mode." } ], "title": "If the private key of a client is compromised, a Session can be hijacked with a ActivateSession when using Sign mode." } ] }