An authorization flaw in MISP allowed an authenticated user to submit a sharing_group_id without verifying that the user was authorized to use the referenced Sharing Group.

In several attribute and Galaxy Cluster creation and editing workflows, validation of the submitted Sharing Group was performed only when the request explicitly set the distribution field to 4 ("Sharing Group"). An attacker could therefore craft a request containing a sharing_group_id while omitting the distribution parameter, or otherwise avoiding the distribution == 4 condition, causing the Sharing Group authorization check to be skipped.

This could allow a user with permission to create or modify the affected MISP objects to associate data with a Sharing Group that they are not authorized to use. Depending on the affected object's existing distribution settings and subsequent processing, this could bypass intended information-sharing boundaries and result in unauthorized placement or distribution of data to members of another Sharing Group.

The issue affected attribute attachment and editing operations as well as Galaxy Cluster creation and editing. The fix ensures that authorization is performed whenever a non-empty sharing_group_id is submitted, independently of the distribution parameter. It also centralizes the authorization decision in SharingGroup::canUse() and explicitly rejects empty Sharing Group identifiers rather than allowing them to be interpreted as an unrestricted query.
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Fixes

Solution

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Workaround

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History

Fri, 04 Sep 2026 11:15:00 +0000

Type Values Removed Values Added
First Time appeared Misp
Misp misp
Vendors & Products Misp
Misp misp

Fri, 04 Sep 2026 09:00:00 +0000

Type Values Removed Values Added
Description An authorization flaw in MISP allowed an authenticated user to submit a sharing_group_id without verifying that the user was authorized to use the referenced Sharing Group. In several attribute and Galaxy Cluster creation and editing workflows, validation of the submitted Sharing Group was performed only when the request explicitly set the distribution field to 4 ("Sharing Group"). An attacker could therefore craft a request containing a sharing_group_id while omitting the distribution parameter, or otherwise avoiding the distribution == 4 condition, causing the Sharing Group authorization check to be skipped. This could allow a user with permission to create or modify the affected MISP objects to associate data with a Sharing Group that they are not authorized to use. Depending on the affected object's existing distribution settings and subsequent processing, this could bypass intended information-sharing boundaries and result in unauthorized placement or distribution of data to members of another Sharing Group. The issue affected attribute attachment and editing operations as well as Galaxy Cluster creation and editing. The fix ensures that authorization is performed whenever a non-empty sharing_group_id is submitted, independently of the distribution parameter. It also centralizes the authorization decision in SharingGroup::canUse() and explicitly rejects empty Sharing Group identifiers rather than allowing them to be interpreted as an unrestricted query.
Title MISP Sharing Group Authorization Bypass via Omitted Distribution Parameter
Weaknesses CWE-862
References
Metrics cvssV4_0

{'score': 7.6, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: CIRCL

Published:

Updated: 2026-09-04T19:37:59.803Z

Reserved: 2026-09-04T08:53:39.237Z

Link: CVE-2026-85533

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-04T09:17:11.857

Modified: 2026-09-04T20:17:32.220

Link: CVE-2026-85533

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-04T11:00:11Z

Weaknesses