Local code execution via unrestricted Jinja2 rendering
Published Apr 21, 2026 · Updated Apr 21, 2026
Code injection in Home Assistant CLI before 1.0.0 allows context-dependent attackers to execute code through a malicious local Jinja2 template. The local template plugin rendered user input with Jinja2 Environment rather than ImmutableSandboxedEnvironment, exposing environment globals and Python built-ins. Exploitation requires a user to obtain the attacker's template and render it with --local; the resulting code runs on that local machine, not the Home Assistant instance.
Summary
What happened
Code injection in Home Assistant CLI before 1.0.0 allows context-dependent attackers to execute code through a malicious local Jinja2 template. The local template plugin rendered user input with Jinja2 Environment rather than ImmutableSandboxedEnvironment, exposing environment globals and Python built-ins. Exploitation requires a user to obtain the attacker's template and render it with --local; the resulting code runs on that local machine, not the Home Assistant instance.
The record
- CVE
- CVE-2026-40602
- Published
- Apr 21, 2026
- Updated
- Apr 21, 2026
- Vendor
- Home Assistant
- Product
- Home Assistant CLI
- Classifications
- CWE-94, CWE-1336, T1059.006, T1204.002
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Apr 21, 2026CVE publishedPublication date reported by the CVE source.
- Apr 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.0.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Vendor advisory Jinja2 built-ins exampleproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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