---
id: CVE-2026-77059
title: TOCTOU Race Condition in boneIO
summary: >-
  boneIO Black contains a TOCTOU race condition in the
  create_timedatectl_sudoers_file() function in
  boneio/webui/routes/timezone_sudoers.py. The function writes sudoers rules to
  a predictable temporary file, validates them, then installs …
severity: high
cvss: 8.8
cvssVector: 'CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H'
cvssSource: cna
cwe:
  - CWE-367
vendor: boneIO
product: boneio
affected:
  - boneio >= 1.3.0 < 1.6.0
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-26T15:30:38.399015Z'
published: '2026-10-26'
updated: '2026-10-26'
sourceUpdated: '2026-10-26T15:35:50.139Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-77059'
references:
  - url: 'https://cert.pl/en/posts/2026/10/CVE-2026-77052'
  - url: 'https://boneio.eu/en/docs/black'
tags:
  - cve.org
ingestedAt: '2026-10-26T15:29:30.512Z'
---

## Overview

boneIO Black contains a TOCTOU race condition in the create_timedatectl_sudoers_file() function in boneio/webui/routes/timezone_sudoers.py. The function writes sudoers rules to a predictable temporary file, validates them, then installs them with root privileges. A local attacker can exploit the race window between validation and installation to substitute malicious content, or use the predictable filename for symlink attacks, resulting in arbitrary sudoers rule injection and local privilege escalation to root.

This issue was fixed in version 1.6.0.

## Affected

- `boneio >= 1.3.0 < 1.6.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.