CVE-2026-76821
OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables.
Overview
CVE-2026-76821 is a known-severity vulnerability. It was published on September 15, 2026.
Technical description
OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to 7.260706.0, the JSON ingestion mapper's extractWithRegexp formula function compiled a user-supplied regular expression with the JavaScript RegExp engine in opencti-platform/opencti-graphql/src/parser/json-mapper.ts without validating its complexity. An authenticated user with JSON mapper creation permission could provide a catastrophically backtracking pattern and matching ingestion input, blocking the Node.js event loop and making the GraphQL API unavailable to all users. Scheduled ingestion could repeatedly execute the malicious mapper without additional attacker action, and recovery could require disabling the mapper and restarting the process. The issue affects availability and does not expose or modify data. This issue is fixed in version 7.260706.0.
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
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Frequently asked questions
What is CVE-2026-76821?
CVE-2026-76821 is a known-severity vulnerability. It was published on September 15, 2026.
How severe is CVE-2026-76821?
CVSS score information is not yet available for this vulnerability. Check back as the CVE record is updated by NVD analysts.
How do I fix or remediate CVE-2026-76821?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-76821?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-76821 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.