{"id":85978,"date":"2025-12-07T00:55:56","date_gmt":"2025-12-07T00:55:56","guid":{"rendered":""},"modified":"-0001-11-30T00:00:00","modified_gmt":"-0001-11-30T00:00:00","slug":"cve-2025-26621-denial-of-service-vulnerability-in-opencti-via-webhook-javascript-execution","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-26621-denial-of-service-vulnerability-in-opencti-via-webhook-javascript-execution\/","title":{"rendered":"CVE-2025-26621: Denial of Service Vulnerability in OpenCTI via Webhook JavaScript Execution<\/strong>"},"content":{"rendered":"

Overview<\/strong><\/p>\n

This report details the CVE-2025-26621 vulnerability that affects OpenCTI, an open-source platform utilized for managing cyber threat intelligence knowledge and observables. The vulnerability is significant due to the potential it carries for system compromise or data leakage, leading to serious consequences for organizations that leverage OpenCTI.<\/p>\n

Vulnerability Summary<\/strong><\/p>\n

CVE ID: CVE-2025-26621
\nSeverity: High (7.6 CVSS score)
\nAttack Vector: Network
\nPrivileges Required: Low
\nUser Interaction: None
\nImpact: Potential system compromise or data leakage, denial of service<\/p>\n

Affected Products<\/strong><\/p>\n

Product | Affected Versions<\/p>\n

OpenCTI | Prior to 6.5.2<\/p>\n

How the Exploit Works<\/strong><\/p>\n

The vulnerability arises from the ability of any user with manage customizations privileges to edit webhook that can execute JavaScript code. If this capability is exploited by a malicious actor, it can lead to prototype pollution that can cause a denial of service attack. This results in the node js server running the OpenCTI frontend becoming unavailable.<\/p>\n

Conceptual Example Code<\/strong><\/p>\n

Below is a conceptual example of how the vulnerability might be exploited. This example depicts a malicious payload within a HTTP request.<\/p>\n

POST \/webhook\/edit HTTP\/1.1\nHost: target.example.com\nContent-Type: application\/json\n{ \"webhook\": \"malicious_javascript_code\" }<\/code><\/pre>\n
The “malicious_javascript_code” would be designed to trigger prototype pollution, leading to a denial-of-service condition on the server.<\/p>\n
Mitigation<\/strong><\/p>\n
The most recommended mitigation strategy involves applying the patch provided by the vendor, which is available in version 6.5.2 of OpenCTI. Alternatively, using a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can offer temporary mitigation. However, these should not replace the necessary action of upgrading to a patched version of OpenCTI to permanently resolve the vulnerability.<\/p>\n","protected":false},"excerpt":{"rendered":"
Overview This report details the CVE-2025-26621 vulnerability that affects OpenCTI, an open-source platform utilized for managing cyber threat intelligence knowledge and observables. The vulnerability is significant due to the potential it carries for system compromise or data leakage, leading to serious consequences for organizations that leverage OpenCTI. Vulnerability Summary CVE ID: CVE-2025-26621 Severity: High (7.6 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"footnotes":""},"categories":[],"tags":[],"vendor":[],"product":[],"attack_vector":[],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-85978","post","type-post","status-publish","format-standard","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t