CVE-2026-102406: 
Kibana vulnerability analysis and mitigation

CVE-2026-102406 is an Authorization Bypass Through User-Controlled Key vulnerability (CWE-639) in Elastic Kibana's Fleet package installation process that enables cross-tenant data interception. An authenticated user with delegated Fleet package-management privileges can claim a data stream identifier already in use by another tenant without ownership verification, redirecting that tenant's data through attacker-controlled infrastructure. Affected versions include Kibana 8.14.0 through 8.19.21, 9.0.0 through 9.4.6, and 9.5.0 through 9.5.3. The vulnerability was published on October 6, 2026, with patches released the same day. It carries a CVSS v3.1 base score of 8.8 (High) (GitHub Advisory, Elastic Advisory).

The root cause is CWE-639 (Authorization Bypass Through User-Controlled Key): Kibana's Fleet package installation process does not verify ownership of a data stream identifier before applying an uploaded package's generated index and ingest-pipeline settings to existing infrastructure. An attacker with only delegated Fleet package-management privileges — not full Elasticsearch administrative access — can craft and upload a Fleet package that claims a data stream name already in use by another tenant. Because the identifier is user-controlled and unchecked, Fleet overwrites the target tenant's index and ingest-pipeline configuration with attacker-controlled settings, effectively hijacking the data stream. Critically, the interception persists even after the malicious package is removed, as the underlying infrastructure changes remain in place until separately remediated (GitHub Advisory, Elastic Advisory).

Successful exploitation allows an authenticated attacker to intercept, read, and modify all data subsequently ingested by the victim tenant's data stream, and to prevent that data from reaching its intended destination — resulting in high confidentiality, integrity, and availability impact. The attack scope is limited to tenants sharing the same Kibana deployment (e.g., users or teams within the same organization), not separate Elastic Cloud organizations. Because the malicious infrastructure changes persist after package removal, affected tenants face ongoing data exposure and disruption until the compromised data streams and ingest pipelines are individually remediated (GitHub Advisory, Elastic Advisory).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time (GitHub Advisory). The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, and NVD SSVC assessment classifies exploitation as "none" and the attack as non-automatable. The EPSS score is approximately 0.354% (27th percentile), indicating a low near-term exploitation probability. Exploitation requires a low-privilege authenticated account with Fleet package-management rights, limiting the attacker pool to internal or compromised users (GitHub Advisory, Elastic Advisory).

1. Reconnaissance: Identify a target Kibana deployment running a vulnerable version (8.14.0–8.19.21, 9.0.0–9.4.6, or 9.5.0–9.5.3) with Fleet enabled and multi-tenant usage.
2. Obtain Fleet privileges: Acquire or compromise an account with delegated Fleet package-management privileges on the shared Kibana deployment (no Elasticsearch admin rights required).
3. Identify target data stream: Enumerate existing data stream identifiers in use by other tenants within the same Kibana deployment to select a target.
4. Craft malicious Fleet package: Create a custom Fleet integration package that declares the target tenant's data stream identifier, with attacker-controlled index templates and ingest pipeline definitions that redirect data to attacker-accessible infrastructure.
5. Upload and install the package: Use the Fleet package installation API or UI to upload and install the crafted package. Because Kibana does not verify ownership of the claimed data stream identifier, it applies the attacker's index and ingest-pipeline settings to the victim's existing infrastructure.
6. Intercept data: All data subsequently ingested by the victim tenant's data stream is now routed through attacker-controlled pipelines, enabling unauthorized reading and modification.
7. Persistence: Even if the malicious package is later removed, the modified index and ingest-pipeline configurations remain in place, sustaining the interception until the victim tenant's infrastructure is separately remediated (GitHub Advisory, Elastic Advisory).

• Logs: Kibana audit logs showing Fleet package installation events by users who do not own or manage the affected data streams; unexpected changes to index template or ingest pipeline configurations associated with another tenant's data streams.
• Fleet/Elasticsearch: Presence of unfamiliar or unauthorized Fleet integration packages referencing data stream names belonging to other tenants; ingest pipeline definitions pointing to unexpected output destinations or containing unfamiliar processors.
• Data Stream Behavior: Victim tenant observing missing, delayed, or corrupted ingested data; data not arriving at its intended index despite successful ingestion attempts.
• Infrastructure: Index templates or ingest pipelines modified at timestamps not corresponding to legitimate administrative activity; pipeline configurations referencing external or unexpected Elasticsearch nodes or outputs (GitHub Advisory, Elastic Advisory).

Elastic has released patched versions addressing this vulnerability: 8.19.22 (for 8.x users), 9.4.7 (for 9.0.x–9.4.x users), and 9.5.4 (for 9.5.x users). Upgrading to one of these versions is the primary recommended remediation. After upgrading, administrators should audit all Fleet package installations and review data stream ownership to identify any unauthorized redirects, then inspect and remediate any compromised index templates and ingest pipelines. No configuration-based workaround is documented; patching is the only definitive fix (Elastic Advisory, GitHub Advisory).

The vulnerability was covered as part of a broader Elastic security update addressing 14 flaws, with security news outlets highlighting CVE-2026-102406 as the most notable issue due to its data interception capability (GBHackers, CyberSecurityNews). The Hacker News included it in their weekly security recap, and community discussion on Mastodon and InfoSec.Exchange noted the persistence of the interception even after package removal as a particularly concerning aspect (The Hacker News, InfoSec.Exchange). No specific threat actor attribution or significant vendor statements beyond the official advisory have been reported.