# Elastic Agent 8.19.21, 9.4.6, 9.5.2 Security Update (ESA-2026-150)

**URL:** <https://discuss.elastic.co/t/elastic-agent-8-19-21-9-4-6-9-5-2-security-update-esa-2026-150/390109>\
**Category:** Security Announcements\
**Created:** [September 1, 2026, 10:33pm UTC](https://discuss.elastic.co/t/elastic-agent-8-19-21-9-4-6-9-5-2-security-update-esa-2026-150/390109 "2026-09-01T22:33:15Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Bryan\_Garcia](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/bryan_garcia/32/148179_2.png) [@Bryan\_Garcia](https://discuss.elastic.co/u/Bryan_Garcia)\
**Post date:** [September 1, 2026, 10:33pm UTC](https://discuss.elastic.co/t/elastic-agent-8-19-21-9-4-6-9-5-2-security-update-esa-2026-150/390109/1 "2026-09-01T22:33:15Z")

</div>

**Incorrect Permission Assignment for Critical Resource in Elastic Agent Leading to Local Privilege Escalation to SYSTEM**

Incorrect Permission Assignment for Critical Resource (CWE-732) in Elastic Agent can lead to local privilege escalation via Replace Binaries (CAPEC-642). On Windows systems where Elastic Agent is installed in unprivileged mode, resources used by the agent service are created with access controls broader than required. A local user could take advantage of this to cause the service to execute code of their choosing, ultimately obtaining SYSTEM-level privileges on the host.

**Affected Versions:**

- 8.x: All versions from 8.0.0 up to and including 8.19.20
- 9.x:
  - All versions from 9.0.0 up to and including 9.4.5
  - All versions from 9.5.0 up to and including 9.5.1

**Affected Configurations:**

Only Windows deployments of Elastic Agent using the unprivileged installation mode are affected. Default (privileged) installations on Windows, and all Linux and macOS deployments, are not affected.

**Solutions and Mitigations:**

The issue is resolved in Elastic Agent versions 8.19.21, 9.4.6, and 9.5.2.

**For Users that Cannot Upgrade:**

Users who cannot immediately upgrade should avoid deploying Elastic Agent in unprivileged installation mode on Windows systems. Switching to a standard (privileged) installation removes the overly permissive access control configuration.

**Indicators of Compromise (IOC)**

No specific indicators of compromise have been identified for this vulnerability.

**Severity:** CVSSv3.1: High ( 7.8 ) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H  
**CVE ID:** CVE-2026-78604  
**Problem Type:** CWE-732 - Incorrect Permission Assignment for Critical Resource  
**Impact:** CAPEC-642 - Replace Binaries