CVE-2026-35210: Citeum Opencti

High severity, CVSS 7.1. EPSS: 0.4% chance of exploitation in the next 30 days.

OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to 7.260326.0, an authorization bypass vulnerability in OpenCTI allows any authenticated user with KNOWLEDGE_KNUPDATE permission to bypass Confidence Level validation and Object Marking restrictions by injecting the synchronized-upsert: true HTTP header, enabling attackers to downgrade confidence levels, remove security markings such as TLP:RED, manipulate relationships, and affect STIX object types including Indicators, ThreatActors, Malware, and Reports. This issue is fixed in version 7.260326.0.

Affected products

• Citeum Opencti: before 7.260326.0 (fixed in 7.260326.0)

Published 2026-07-08. Last modified 2026-07-13.