What is the CVSS score of EUVD-2026-58288?

EUVD-2026-58288 has a CVSS 3.1 base score of 7.1 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N. EPSS exploitation probability: 0.3%.

Which versions of Kibana Agent Builder are affected by EUVD-2026-58288?

Kibana Agent Builder's authorization flaw exposes organizations using federated authentication to unauthorized workflow access-an attacker with valid credentials can modify or delete automation owned…

How to fix or mitigate EUVD-2026-58288?

Within 24 hours, identify all Kibana deployments using Agent Builder and document which authentication realms are enabled; verify username uniqueness across all configured realms. Within 7 days, implement network-layer access restrictions to Agent Builder, enforce strict role-based access control limiting builder access to essential personnel, and enable comprehensive audit logging of all agent creation, modification, and deletion events. Within 30 days, conduct a forensic audit of agent access logs for evidence of cross-realm identity confusion, evaluate migration to stable user identifier schemes (e.g., UUIDs or email-based identifiers), and establish a process to apply any vendor-released patches immediately upon availability.

Kibana Agent Builder EUVD-2026-58288

| CVE-2026-72643 HIGH

Incorrect Authorization (CWE-863)

2026-08-13 elastic

GHSA-m5pm-2p35-xvpr

Authentication Bypass Elastic Kibana

7.1

CVSS 3.1 · Vendor: elastic

Severity by source

Vendor (elastic) PRIMARY

7.1 HIGH

AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

vuln.today AI

7.1 HIGH

Network-reachable via Kibana API, low complexity once realm overlap exists, low-privilege authenticated session required, high confidentiality impact on agent config, low integrity impact from modification or deletion.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

4.0 AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (elastic).

CVSS VectorVendor: elastic

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Aug 13, 2026 - 19:56 vuln.today

CVE Published

Aug 13, 2026 - 19:13 cve.org

HIGH 7.1

DescriptionCVE.org

Kibana Agent Builder determines whether a caller owns a private agent by comparing a stable user identifier when one is recorded, and falling back to a comparison of the username when it is not. A username is not unique across Elasticsearch authentication realms, so two distinct principals that share a username in different realms are treated as the same owner. This discloses the configuration and instructions of an agent the caller does not own, and allows that agent to be altered or removed.

AnalysisAI

Incorrect authorization in Kibana Agent Builder allows authenticated users to access, modify, or delete private agents they do not own when sharing a username with another principal across different Elasticsearch authentication realms. The flaw stems from a fallback ownership check that compares usernames - which are not unique across realms - rather than stable user identifiers, enabling cross-realm identity confusion. No public exploit or active exploitation (CISA KEV) has been identified at time of analysis, but the low attack complexity and network accessibility make this a credible insider or multi-tenant threat.

Technical ContextAI

Kibana Agent Builder is a feature within Elastic's Kibana UI (CPE: cpe:2.3:a:elastic:kibana:*:*:*:*:*:*:*:*) that allows users to create and manage private AI agents with custom configurations and instructions. Elasticsearch supports multiple authentication realms simultaneously - for example, a native realm alongside an LDAP or Active Directory realm - and a 'username' string is only unique within a single realm, not globally across the stack. The Agent Builder's ownership check uses a stable user identifier (such as a realm-scoped principal UID) as the primary comparator, but silently falls back to a plain username string comparison when no stable identifier is recorded. This fallback is the vulnerable code path: CWE-863 (Incorrect Authorization) describes exactly this pattern, where an authorization decision is made using an insufficiently precise principal identity. An attacker in Realm A whose username matches a victim in Realm B can exploit the fallback path to be incorrectly treated as the same owner.

RemediationAI

Upgrade Kibana to version 9.4.5 or 9.5.1 per Elastic security advisory ESA-2026-124 (https://discuss.elastic.co/t/kibana-9-4-5-9-5-1-security-update-esa-2026-124/389538). These are the patch versions identified in the advisory title; no earlier patched minor release has been confirmed. If immediate upgrade is not possible, a targeted compensating control is to audit and eliminate username collisions across all configured Elasticsearch authentication realms - ensuring no two principals in different realms share an identical username string removes the condition that triggers the fallback code path. This control has a trade-off: it may require coordinated username changes with identity providers (LDAP/AD) and could disrupt existing user mappings. A second workaround is to restrict Agent Builder usage to a single authentication realm by temporarily disabling multi-realm configurations, though this may impact SSO or identity federation workflows. Do not rely on access controls at the network perimeter alone, as any authenticated Kibana user in a multi-realm deployment can trigger this flaw.