CVE-2026-85226 in MISP
Summary
by MITRE • 09/03/2026
MISP contains an authorization flaw in the OnDemand correlation engine where correlations were calculated solely from matching attribute values without applying the distribution, sharing group, organization, or other access-control restrictions associated with the correlated attributes and events. As a result, an authenticated user could receive correlation results referring to attributes or events that the user was not authorized to access.
The vulnerable correlation collection path did not take the requesting user into account. The patch changes the correlation collector to accept the current user and filters the resulting attribute identifiers through MISP's existing fetchAttributesSimple() authorization logic, which evaluates event-, attribute-, object-, distribution-, and sharing-group-level restrictions against the live data.
The issue also affected paths relying on previously stored correlation data. Because the OnDemand engine does not maintain the stored correlation table, its denormalized access-control information could be stale. The patch therefore validates correlated attribute identifiers against the current ACLs before returning them and additionally applies normal event visibility conditions when retrieving related events.
An authenticated low-privileged user could exploit this issue by querying or creating attributes that correlate with restricted MISP content, potentially learning information about otherwise inaccessible events or attributes.
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Analysis
by VulDB Data Team • 09/03/2026
The vulnerability identified in the Malware Information Sharing Platform (MISP) represents a critical authorization bypass within its OnDemand correlation engine. This flaw stems from an architectural oversight where the mechanism responsible for calculating correlations between indicators of compromise and other threat intelligence data failed to enforce standard access control policies. Specifically, when users queried for correlated attributes or events, the system performed matching based solely on value equivalence without considering the distribution settings, sharing group memberships, organizational boundaries, or other granular access-control restrictions that typically govern visibility in MISP. Consequently, an authenticated user could retrieve correlation results pointing to sensitive attributes or events that were explicitly restricted from their view, effectively bypassing the platform's intended security model and exposing confidential threat intelligence data to unauthorized personnel.
From a technical perspective, the root cause lies in the design of the vulnerable correlation collection path, which operated independently of the requesting user context. The original implementation did not pass user identity or permission sets into the correlation logic, leading to results that were agnostic to individual privileges. This deficiency was compounded by the handling of previously stored correlation data. Since the OnDemand engine does not maintain a persistent, denormalized table with up-to-date access control lists, any cached or pre-computed correlations could contain stale security metadata. Even if an attribute had been restricted after initial indexing, older correlation entries might still reference it without proper validation against current permissions, allowing legacy data to leak information that should have been obscured by updated policy changes.
The operational impact of this vulnerability is significant for organizations relying on MISP for secure threat intelligence sharing. An authenticated low-privileged user could exploit this flaw by crafting queries or creating attributes designed to correlate with high-sensitivity content. By doing so, they could infer the existence and potentially the nature of restricted events or attributes that are otherwise invisible in their standard interface views. This capability undermines the principle of least privilege and compromises the confidentiality of shared intelligence, particularly in multi-tenant environments where different organizations share a single MISP instance but require strict data isolation to protect proprietary threat research or sensitive operational details from competitors or unauthorized internal stakeholders.
To address this issue, developers implemented a patch that fundamentally alters how correlation results are processed before being returned to the user. The updated correlation collector now accepts the current user context and filters all resulting attribute identifiers through MISP's existing fetchAttributesSimple() authorization logic. This function rigorously evaluates event-level, attribute-level, object-level, distribution-level, and sharing-group-level restrictions against live data permissions. Furthermore, for paths relying on stored correlation data, the patch introduces a validation step that checks correlated attribute identifiers against current access control lists before inclusion in results. Additionally, normal event visibility conditions are applied when retrieving related events to ensure that even if an identifier is validly correlated, the associated context remains hidden from users lacking appropriate clearance.
This vulnerability aligns with CWE-269, which describes Improper Privilege Management, specifically regarding insufficient authorization checks for critical functions. In terms of offensive security frameworks such as MITRE ATT&CK, this flaw facilitates unauthorized data access and potentially aids in reconnaissance activities by allowing attackers to map out the structure and sensitivity levels of hidden threat intelligence assets within a shared instance. Remediation requires immediate application of the provided patch to ensure that all correlation queries are subject to real-time authorization checks. Organizations should also verify their user role configurations to ensure that low-privileged accounts do not possess unnecessary permissions for creating attributes or initiating correlations, thereby reducing the attack surface even if similar vulnerabilities were present in other components of the platform.