CVE-2026-85236
Undergoing Analysis Undergoing Analysis - In Progress

CSRF in MISP Leading to Unauthorized Event Deletion

Vulnerability report for CVE-2026-85236, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-09-03

Last updated on: 2026-09-03

Assigner: CIRCL

Description

A cross-site request forgery (CSRF) vulnerability existed in the cullEmptyEvents action of MISP. The endpoint performed a state-changing and irreversible operation while accepting HTTP GET requests. Because bodyless GET requests are not subject to CakePHP's CSRF validation, an attacker could cause an authenticated MISP user with sufficient privileges to invoke the endpoint simply by causing their browser to load a crafted URL, for example through an embedded image or other automatically requested resource. Successful exploitation triggers the deletion of published empty events. The deletion is particularly significant because the operation uses skipBlocklist, meaning the removed events do not leave blocklist entries that could prevent or track their subsequent synchronization. This can result in unintended and potentially irreversible deletion of MISP event records without explicit user interaction. The vulnerability was addressed by restricting cullEmptyEvents to HTTP POST requests, ensuring that CakePHP's normal CSRF protections are applied to the operation.

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Meta Information

Published
2026-09-03
Last Modified
2026-09-03
Generated
2026-09-03
AI Q&A
2026-09-03
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
misp misp *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-352 The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.

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Executive Summary

This is a Cross-Site Request Forgery (CSRF) vulnerability in MISP where the cullEmptyEvents action could be triggered via HTTP GET requests. Since GET requests without a body bypass CakePHP's CSRF validation, attackers could exploit this by causing a user's browser to load a malicious URL, such as through an embedded image. Successful exploitation deletes published empty events irreversibly without leaving blocklist entries for tracking.

Detection Guidance

Check MISP server logs for unusual GET requests targeting the cullEmptyEvents endpoint. Look for repeated requests from the same IP or unexpected event deletions. Verify if the endpoint is restricted to POST requests only by inspecting server configuration files.

Impact Analysis

An attacker could trick an authenticated MISP user with sufficient privileges into triggering the deletion of empty events by visiting a crafted URL. This could lead to unintended loss of event records, especially since deleted events do not leave blocklist entries for recovery or synchronization tracking.

Mitigation Strategies

Update MISP to the latest patched version where cullEmptyEvents is restricted to POST requests. Review server configurations to ensure all state-changing endpoints enforce POST methods. Monitor for unauthorized event deletions and block suspicious GET requests to vulnerable endpoints.

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