CVE-2026-85227: Misp XSS (CVSS 6.1)

Description

MISP contains a reflected Cross-Site Scripting (XSS) vulnerability in the event attribute filtering query builder. The taggedAttributes and galaxyAttachedAttributes URL parameters were inserted into the query-builder rules without HTML escaping before being serialized as JSON and embedded inside a <script> element. Because JsonTool::encode() uses JSON_UNESCAPED_SLASHES, an attacker-controlled value containing a closing </script> sequence could terminate the surrounding script element and inject arbitrary HTML or JavaScript. For example, a specially crafted viewEventAttributes URL could contain malicious content in one of the affected filter parameters. An attacker could exploit the vulnerability by convincing an authenticated MISP user to follow a crafted URL. Successful exploitation would execute attacker-controlled JavaScript in the security context of the MISP instance and with the privileges of the victim's authenticated browser session. This could allow access to information available to the victim, modification of data through authenticated requests, or other actions permitted by the victim's MISP permissions. The vulnerability is addressed by applying HTML escaping with h() to both scalar and array values before they are inserted into the DOM.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS 4.0

6.1/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:H/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

EPSS Probability

0.27%

19.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Misp-Project	Misp	< 2.5.46

References

https://github.com/MISP/MISP/commit/de51a16dbPatch

Timeline

Published: Sep 3, 2026
Last Modified: Sep 10, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-85227?

MISP contains a reflected Cross-Site Scripting (XSS) vulnerability in the event attribute filtering query builder. The taggedAttributes and galaxyAttachedAttributes URL parameters were inserted into the query-builder rules without HTML escaping before being serialized as JSON and embedded inside a <script> element. Because JsonTool::encode() uses JSON_UNESCAPED_SLASHES, an attacker-controlled value containing a closing </script> sequence could terminate the surrounding script element and inject arbitrary HTML or JavaScript. For example, a specially crafted viewEventAttributes URL could contain malicious content in one of the affected filter parameters. An attacker could exploit the vulnerability by convincing an authenticated MISP user to follow a crafted URL. Successful exploitation would execute attacker-controlled JavaScript in the security context of the MISP instance and with the privileges of the victim's authenticated browser session. This could allow access to information available to the victim, modification of data through authenticated requests, or other actions permitted by the victim's MISP permissions. The vulnerability is addressed by applying HTML escaping with h() to both scalar and array values before they are inserted into the DOM.

How severe is CVE-2026-85227?

CVE-2026-85227 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.

How do I fix CVE-2026-85227?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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