CVE-2026-81820
Flowintel HTML Injection in MISP Case History Timeline via Crafted Object Attributes
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
INFO
Published Date :
Aug. 27, 2026, 5:21 p.m.
Last Modified :
Aug. 27, 2026, 8:18 p.m.
Remotely Exploit :
Yes !
Source :
5a6e4751-2f3f-4070-9419-94fb35b644e8
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | MEDIUM | 5a6e4751-2f3f-4070-9419-94fb35b644e8 | ||||
| CVSS 4.0 | MEDIUM | 5a6e4751-2f3f-4070-9419-94fb35b644e8 |
Solution
- Update Flowintel to version 3.3.0 or later.
- Replace string interpolation with DOM construction.
- Assign values using textContent.
- Escape HTML via a temporary element.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-81820.
| URL | Resource |
|---|---|
| https://github.com/flowintel/flowintel/commit/11f71e747d95ed062667e2df0ce259c5fa64d531.patch |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-81820 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-81820
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-81820 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-81820 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 27, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-81820', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-27T19:39:14.593497Z'} -
New CVE Received by 5a6e4751-2f3f-4070-9419-94fb35b644e8
Aug. 27, 2026
Action Type Old Value New Value Added 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 Added CVSS V4.0 AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-79 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/81xxx/CVE-2026-81820.json">CVE-2026-81820</a> Added Reference https://github.com/flowintel/flowintel/commit/11f71e747d95ed062667e2df0ce259c5fa64d531.patch