CVE-2026-85538
Received Received - Intake

Incorrect Authorization in MISP Allows Attribute Deletion Without Permissions

Vulnerability report for CVE-2026-85538, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: CIRCL

Description

An incorrect authorization vulnerability in MISP allowed authenticated users to delete attributes from events despite lacking the required perm_modify or perm_modify_org permissions. The affected attribute deletion paths relied on organization membership checks performed by MispAttribute::deleteAttribute() but did not consistently enforce MISP's event modification authorization rules. Consequently, a user belonging to the organization associated with an event could potentially delete individual attributes or perform bulk attribute deletion even when their assigned role was not authorized to modify the event. This created an inconsistency between attribute editing and deletion: editing an attribute correctly used MISP's ACL::canModifyEvent() authorization logic, whereas the affected deletion operations could bypass these permission checks. An authenticated attacker with access to an affected MISP instance and membership in the organization owning an event could exploit this flaw to remove attributes from that event, potentially causing unauthorized modification or loss of threat intelligence data. The patch introduces a common authorization check for all affected deletion paths. Before deletion, MISP now resolves the associated events and verifies that the current user is authorized to modify each event using the same authorization mechanism used by normal event and attribute modification operations.

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Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-04
AI Q&A
2026-09-04
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-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

Attack-Flow Graph

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Executive Summary

This vulnerability in MISP (Malware Information Sharing Platform) is an incorrect authorization issue where authenticated users could delete attributes from events without having the required perm_modify or perm_modify_org permissions. The problem occurred because attribute deletion paths only checked organization membership but not event modification authorization rules, creating a bypass in permission checks.

Detection Guidance

This vulnerability can be detected by reviewing MISP event logs for unauthorized attribute deletions. Check for users deleting attributes without proper perm_modify or perm_modify_org permissions. Review the commit diff in Resource 1 to identify affected code paths.

Impact Analysis

An authenticated attacker with access to a vulnerable MISP instance and membership in the organization owning an event could exploit this flaw to remove attributes from that event. This could lead to unauthorized modification or loss of threat intelligence data, potentially disrupting security operations and sharing of critical information.

Compliance Impact

This vulnerability could impact compliance with GDPR and HIPAA by allowing unauthorized users to delete threat intelligence data, potentially violating data integrity and access control requirements. Unauthorized attribute deletion may lead to loss of critical security information, affecting audit trails and data protection measures required by these regulations.

Mitigation Strategies

Apply the security patch from Resource 1 immediately. Ensure all MISP instances are updated to the latest version. Review user permissions to confirm only authorized users have attribute deletion capabilities.

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