CVE-2026-71259

ESPHome external_components file:// Scheme Validation Bypass Leading to Remote Code Execution

Published Aug 5, 2026 CVSS 3.1 · 8.6 High EPSS < 1% KEV · Not listed
Description
ESPHome through 2026.7.0-dev contains an operator-precedence bug in the cv.url validator in esphome/config_validation.py. Because binds tighter than , any file: URI passes validation regardless of netloc. This validator gates the field of the external_components YAML directive's git source schema, which is passed to (git supports file:// natively).

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Description ESPHome through 2026.7.0-dev contains an operator-precedence bug in the cv.url() validator in esphome/config_validation.py: `if parsed.scheme and parsed.netloc or parsed.scheme == "file": return parsed.geturl()`. Because `and` binds tighter than `or`, any file: URI passes validation regardless of netloc. This validator gates the `url:` field of the external_components YAML directive's git source schema, which is passed to `git clone` (git supports file:// natively). A crafted `external_components` block with `url: "file:///attacker/repo"` clones an attacker-controlled local path, which is then added to Python's import machinery via ESPHome's component loader, executing arbitrary Python code when the YAML configuration is processed (e.g. via `esphome config`/`esphome run`). ESPHome through 2026.7.0-dev contains an operator-precedence bug in the cv.url validator in esphome/config_validation.py. Because binds tighter than , any file: URI passes validation regardless of netloc. This validator gates the field of the external_components YAML directive's git source schema, which is passed to (git supports file:// natively).
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Esphome
Esphome esphome
Vendors & Products Esphome
Esphome esphome
Type Values Removed Values Added
Description ESPHome through 2026.7.0-dev contains an operator-precedence bug in the cv.url() validator in esphome/config_validation.py: `if parsed.scheme and parsed.netloc or parsed.scheme == "file": return parsed.geturl()`. Because `and` binds tighter than `or`, any file: URI passes validation regardless of netloc. This validator gates the `url:` field of the external_components YAML directive's git source schema, which is passed to `git clone` (git supports file:// natively). A crafted `external_components` block with `url: "file:///attacker/repo"` clones an attacker-controlled local path, which is then added to Python's import machinery via ESPHome's component loader, executing arbitrary Python code when the YAML configuration is processed (e.g. via `esphome config`/`esphome run`).
Title ESPHome external_components file:// Scheme Validation Bypass Leading to Remote Code Execution
Weaknesses CWE-184
References
Metrics cvssV3_1

{'score': 8.6, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
TuranSec
Published
Updated
Aug 10, 2026, 11:46 AM
Reserved
Aug 5, 2026, 12:23 PM
Status
Deferred
Published
Aug 5, 2026, 1:24 PM
Modified
Aug 26, 2026, 5:13 PM