CVE-2026-78596: 
Kibana vulnerability analysis and mitigation

CVE-2026-78596 is a Missing Authorization vulnerability (CWE-862) in Elastic Kibana that allows authenticated users with limited privileges to perform unauthorized data modifications. An authenticated user holding Security read-level access in a single Kibana space can trigger Entity Analytics migration operations that perform privileged writes across all Kibana spaces, exceeding their intended access scope. Affected versions include Kibana 8.18.3–8.19.20, 9.0.3–9.4.5, and 9.5.0–9.5.2. It was published on September 3, 2026, and carries a CVSS v3.1 base score of 4.3 (Medium) (GitHub Advisory, Elastic Advisory).

The root cause is a missing authorization check (CWE-862) in Kibana's Entity Analytics migration operations, exploitable via Privilege Abuse (CAPEC-122). When a user with Security read-level access in one Kibana space initiates an Entity Analytics migration, the application fails to verify whether that user has write permissions across all Kibana spaces before executing the operation. This allows the migration routine to perform privileged writes beyond the user's authorized scope, effectively bypassing Kibana's space-based access control model. No public proof-of-concept code has been identified (GitHub Advisory, Elastic Advisory).

Successful exploitation allows an authenticated attacker with minimal privileges (Security read-level in a single space) to modify data across all Kibana spaces without authorization. The primary impact is on data integrity — confidentiality and availability are not directly affected. In environments where multiple teams or tenants share a Kibana deployment with space-based isolation, this vulnerability could allow a low-privileged user to corrupt or tamper with Entity Analytics data belonging to other spaces, undermining the integrity of security analytics workflows (GitHub Advisory, Elastic Advisory).

There is no evidence of active in-the-wild exploitation or publicly available proof-of-concept code for CVE-2026-78596. The EPSS score is approximately 0.152%, indicating a low probability of exploitation in the near term. The NVD SSVC assessment classifies exploitation as "none" and the attack as non-automatable, reflecting the requirement for authenticated access and manual triggering of migration operations. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog (GitHub Advisory, Elastic Advisory).

1. Authenticate to Kibana: Log in to a vulnerable Kibana instance (versions 8.18.3–8.19.20, 9.0.3–9.4.5, or 9.5.0–9.5.2) using credentials for an account that has at minimum Security read-level access in any single Kibana space.
2. Identify Entity Analytics migration endpoint: Locate the Kibana API endpoint or UI action responsible for triggering Entity Analytics migration operations within the accessible space.
3. Trigger migration operation: Initiate the Entity Analytics migration operation from within the space where the attacker has read-level access. Due to the missing authorization check, the backend will execute privileged write operations without verifying cross-space permissions.
4. Achieve cross-space data modification: The migration operation performs privileged writes across all Kibana spaces, allowing the attacker to modify Entity Analytics data in spaces they are not authorized to access (GitHub Advisory, Elastic Advisory).

• Logs: Kibana audit logs showing Entity Analytics migration operations initiated by users with only Security read-level roles, particularly if those operations affect multiple spaces beyond the user's assigned space.
• Logs: Unexpected write activity in Kibana spaces by users whose role assignments do not include write permissions for those spaces.
• Logs: Kibana server logs recording cross-space data modification events triggered from a single low-privileged user session.
• Network: API calls to Entity Analytics migration endpoints from authenticated sessions associated with read-only security roles (Elastic Advisory).

Elastic has released patched versions addressing this vulnerability: Kibana 8.19.21, 9.4.6, and 9.5.3. Users should upgrade to one of these fixed versions as the primary remediation. As an interim measure, administrators should review and audit Kibana user roles, ensuring that users with Security read-level access are limited to the minimum necessary permissions, and monitor for unexpected Entity Analytics migration activity. Restricting access to Entity Analytics migration operations to only highly privileged users can reduce exposure until patching is complete (Elastic Advisory, GitHub Advisory).

Elastic published an official security advisory (ESA-2026-154) disclosing the vulnerability and providing patched versions on September 3, 2026. No notable independent researcher commentary or significant social media discussion has been identified beyond standard vulnerability aggregator coverage (Elastic Advisory).