CVE-2026-91857
Received Received - Intake

CSRF Protection Bypass in MISP via GET Requests

Publication date: 2026-09-15

Last updated on: 2026-09-15

Assigner: CIRCL

Description
Affected versions of MISP expose several state-changing controller actions without restricting them to POST. The affected actions are:  - EventReportsController::purgeUnusedPictures()  - NoticelistsController::enableNoticelist()  - ServersController::removeOrphanedCorrelations()  - WorkflowsController::rebuildRedis() The patch adds allowMethod(['post']) to each action, preventing them from being triggered through ordinary GET requests. For purgeUnusedPictures(), the corresponding UI previously used $.get(). The fix converts that request to POST and supplies X-CSRF-Token, while the controller enables header-only CSRF validation for that AJAX action. Because GET requests can be induced cross-origin through links, images, redirects, or navigation, accepting GET for these state-changing operations can let an attacker trigger them using the authenticated victim's session. Version affected: ≤2.5.45

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Meta Information

Published
2026-09-15
Last Modified
2026-09-15
Generated
2026-09-15
AI Q&A
2026-09-15
EPSS Evaluated
N/A
NVD
CVE-2026-91857
EUVD
EUVD-2026-78348

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
misp misp to 2.5.45 (inc)

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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

CVE-2026-91857 affects MISP versions 2.5.45 and earlier. It involves four controller actions that were accepting GET requests despite performing state-changing operations. This allows Cross-Site Request Forgery (CSRF) attacks where an attacker could trick a user into triggering these actions via malicious links or redirects.

Detection Guidance

To detect this vulnerability, check if the affected MISP actions (purgeUnusedPictures, enableNoticelist, removeOrphanedCorrelations, rebuildRedis) are accessible via GET requests. Inspect network traffic for GET requests to these endpoints or review server logs for suspicious GET requests to these paths.

Impact Analysis

An attacker could exploit this to perform unauthorized actions on your behalf, such as deleting data, enabling or disabling features, or rebuilding system caches. This requires the victim to be authenticated and the action to be triggered via a GET request.

Mitigation Strategies

Update MISP to version 2.5.46 or later. Ensure the patch adding allowMethod(['post']) to the affected controllers is applied. Verify that state-changing actions now require POST requests and include CSRF tokens for AJAX calls.

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