CVE-2026-21887
7.7 · HIGHOverview
CVE-2026-21887 is a high-severity vulnerability affecting citeum opencti. It was published on March 12, 2026 and has a CVSS 3.1 base score of 7.7 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.7, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
Technical Description
OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to 6.8.16, the OpenCTI platform’s data ingestion feature accepts user-supplied URLs without validation and uses the Axios HTTP client with its default configuration (allowAbsoluteUrls: true). This allows attackers to craft requests to arbitrary endpoints, including internal services, because Axios will accept and process absolute URLs. This results in a semi-blind SSRF, as responses may not be fully visible but can still impact internal systems. This vulnerability is fixed in 6.8.16.
Remediation
Check the references section for vendor advisories and patches from citeum. Update opencti to the latest patched version. 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.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| citeum | opencti | >= 0, < 6.8.16 | Affected |
Frequently Asked Questions
What is CVE-2026-21887?
CVE-2026-21887 is a high-severity vulnerability affecting citeum opencti. It was published on March 12, 2026 and has a CVSS 3.1 base score of 7.7 (HIGH).
How severe is CVE-2026-21887?
This vulnerability has a CVSS 3.1 base score of 7.7, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2026-21887?
Check the references section for vendor advisories and patches from citeum. Update opencti to the latest patched version. 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-2026-21887?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-21887 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
AI-driven PR review catches vulnerable dependencies before they ship.
Browser-based exploitation validates findings with real proof-of-concept.
Related HIGH CVEs from 2026
View all →H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there
OpenProject is an open-source, web-based project management software. To enable the real time collab
OpenSift is an AI study tool that sifts through large datasets using semantic search and generative
Budibase is a low code platform for creating internal tools, workflows, and admin panels. In 3.24.0
FileBrowser Quantum is a free, self-hosted, web-based file manager. Prior to 1.3.1-beta and 1.2.2-st
Shopware is an open commerce platform. Prior to 6.6.10.15 and 6.7.8.1, a vulnerability in the Shopwa
ChurchCRM is an open-source church management system. Prior to 7.1.0, a stored cross-site scripting
A Stored Cross-Site Scripting vulnerability was discovered in the Assets and Nodes functionality due
Postiz is an AI social media scheduling tool. Prior to version 2.21.6, a file upload validation bypa
A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that a
Cross-Site Scripting (XSS) vulnerability exists in HTMLy version 3.1.1 in the content creation funct
An Improper Certificate Validation in Ivanti EPMM before versions 12.6.1.1, 12.7.0.1, and 12.8.0.1 a