CVE-2026-81820: XSS

Description

Affected versions of Flowintel construct timeline HTML using attacker-controllable MISP object fields such as: * object UUID; * object name; * attribute value; * attribute type; * comment; * first/last seen values; * IDS flag. Those values were concatenated directly into HTML strings before rendering. The upstream commit explicitly states that DOMPurify removed XSS vectors but still allowed other HTML elements, such as forms, through. The fix replaces direct string interpolation with DOM construction via document.createElement() and assigns all attacker-controlled values using textContent. The headline is similarly converted to escaped HTML through a temporary element. Version impacted =>3.3.0

Is your site exposed to CVE-2026-81820?

Run a free security scan — no signup, results in seconds.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/flowintel/flowintel/commit/11f71e747d95ed062667e2df0ce259c5fa64d531.patch

Frequently Asked Questions

What is CVE-2026-81820? +

Affected versions of Flowintel construct timeline HTML using attacker-controllable MISP object fields such as: * object UUID; * object name; * attribute value; * attribute type; * comment; * first/last seen values; * IDS flag. Those values were concatenated directly into HTML strings before rendering. The upstream commit explicitly states that DOMPurify removed XSS vectors but still allowed other HTML elements, such as forms, through. The fix replaces direct string interpolation with DOM construction via document.createElement() and assigns all attacker-controlled values using textContent. The headline is similarly converted to escaped HTML through a temporary element. Version impacted =>3.3.0

How do I check if I'm vulnerable to CVE-2026-81820? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-40282

WeGIA is a web manager for charitable institutions. In versions prior to 3.6.10, a Stored Cross-Site Scripting (XSS) vulnerability allows …

CVE-2026-3317

Reflected Cross-Site Scripting (XSS) vulnerability in Navigate Content Management System. The vulnerability is present in the '/blog' endpoint because user …

CVE-2025-10354

Cross-Site Scripting (XSS) vulnerability reflected in Semantic MediaWiki. This vulnerability allows an attacker to execute JavaScript code in the victim's …

CVE-2026-41456

Bludit CMS prior to commit 6732dde contains a reflected cross-site scripting vulnerability in the search plugin that allows unauthenticated attackers …

CVE-2026-40872

mailcow: dockerized is an open source groupware/email suite based on docker. In versions prior to 2026-03b, the admin dashboard's Autodiscover …

CVE-2026-40878

mailcow: dockerized is an open source groupware/email suite based on docker. In versions prior to 2026-03b, the mailcow web interface …

CVE-2026-81820