CVE-2026-76820
HighCVSS 7.7Exploitation Probability (EPSS)
Low risk23th percentile - higher than 23% of all known CVEs
Summary
OpenCTI before version 7.260701.0 has a vulnerability in the synchronizerFetch GraphQL query, which calls fetchRemoteStreams after only checking that the remote stream URL uses HTTP or HTTPS. The backend does not apply the ingestion deny list or reject private, loopback, and link-local destinations, allowing an authenticated account with INGESTION capability to make OpenCTI request internal services and cloud metadata endpoints. Connection errors can enable internal network scanning, and compatible responses may disclose internal data.
Risk Assessment
The risk includes potential internal network scanning and disclosure of internal data, which could lead to further attacks within the organization's infrastructure.
Recommendation
Upgrade OpenCTI to version 7.260701.0 or later and configure network firewalls to block traffic to private and cloud metadata addresses from the platform.
Other vulnerabilities in OpenCTI
See all- CVE-2025-61781High
OpenCTI before version 6.8.1 contains a vulnerability in the GraphQL mutation WorkspacePopoverDeletionMutation that allows deletion of workspace-related objects (e.g., dashboards, investigation cases) without proper authorization. An attacker can supply another user's active UUID and delete the entire workspace because the API does not validate ownership.
- CVE-2026-27960Critical
In OpenCTI, versions 6.6.0 through 6.9.12, there is a privilege escalation vulnerability that can be exploited by unauthenticated attackers to query the API as any existing user, including the default admin account.
- CVE-2026-76821High
OpenCTI before version 7.260706.0 has a vulnerability in the extractWithRegexp function of the JSON ingestion mapper, which compiles user-supplied regular expressions without validating complexity. An authenticated user with JSON mapper creation permission can provide a catastrophic backtracking pattern, blocking the Node.js event loop and making the GraphQL API unavailable. Scheduled ingestion could repeatedly execute the malicious mapper without additional action.
- CVE-2026-35211Medium
OpenCTI GraphQL API exposes a script filter operator in its FilterOperator enum that allows authenticated users with KNOWLEDGE capability to pass unsanitized Elasticsearch Painless scripts into search queries. This can cause CPU resource exhaustion and denial of service for all users.
- CVE-2026-35210High
In OpenCTI prior to version 7.260326.0, an authorization bypass vulnerability 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. This enables attackers to downgrade confidence levels, remove security markings like TLP:RED, manipulate relationships, and affect STIX object types including Indicators, ThreatActors, Malware, and Reports.
- CVE-2026-35212Medium
OpenCTI versions prior to 7.260227.0 are vulnerable to XSS in the rendering of email-message observable body data. The content of the body field isn't appropriately sanitized when being rendered. Requires user interaction but could be exploited by someone sharing STIX or any of the ingester.
- CVE-2026-44730High
OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to 6.9.7, an organization admin can escalate their privileges by adding a user from a different organization with higher privileges to their own organization. This is due to incorrect ACL on userEdit relationAdd. This vulnerability is fixed in 6.9.7.
Original NVD description (English source)
OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to 7.260701.0, the synchronizerFetch GraphQL query called fetchRemoteStreams after checking only that a remote stream URL used HTTP or HTTPS. The backend did not apply the ingestion deny list or reject private, loopback, and link-local destinations, allowing an authenticated account with the INGESTION capability to make OpenCTI request internal services and cloud metadata endpoints. Returned connection errors could distinguish open HTTP ports, open non-HTTP ports, and closed ports, enabling internal network scanning, while compatible endpoint responses could disclose internal data. This issue is fixed in version 7.260701.0.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

