---
id: CVE-2016-2568
title: >-
  pkexec, when used with --user nonpriv, allows local users to escape to the
  parent session via a crafted TIOCSTI ioctl call, which pushes characters to
  the terminal's input buffer.
summary: >-
  pkexec, when used with --user nonpriv, allows local users to escape to the
  parent session via a crafted TIOCSTI ioctl call, which pushes characters to
  the terminal's input buffer.
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H'
cwe:
  - CWE-116
vendor: freedesktop
product: polkit
affected:
  - polkit
  - enterprise_linux = 6.0
  - enterprise_linux = 7.0
published: '2017-02-13'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T22:16:38.407'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2016-2568'
references:
  - url: 'http://www.openwall.com/lists/oss-security/2016/02/26/3'
    label: cve@mitre.org
  - url: 'https://access.redhat.com/security/cve/cve-2016-2568'
    label: cve@mitre.org
  - url: 'https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=816062'
    label: cve@mitre.org
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=1300746'
    label: cve@mitre.org
  - url: 'https://ubuntu.com/security/CVE-2016-2568'
    label: cve@mitre.org
  - url: 'http://www.openwall.com/lists/oss-security/2016/02/26/3'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://access.redhat.com/security/cve/cve-2016-2568'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=816062'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=1300746'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://ubuntu.com/security/CVE-2016-2568'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00366
epssPercentile: 0.28384
ingestedAt: '2026-10-08T23:16:47.282Z'
---

## Overview

pkexec, when used with --user nonpriv, allows local users to escape to the parent session via a crafted TIOCSTI ioctl call, which pushes characters to the terminal's input buffer.

## Affected

- `polkit`
- `enterprise_linux = 6.0`
- `enterprise_linux = 7.0`

## Remediation

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