Enterprise LinuxOperating system · Redhat
CVE-2016-2568
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedpkexec, 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe pkexec utility in polkit, when invoked with the --user nonpriv option, allows local users to escape to the parent terminal session by using a crafted TIOCSTI ioctl call. This ioctl pushes characters directly into the terminal's input buffer, enabling command injection or session hijacking from the unprivileged pkexec subprocess back to the user's parent shell.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Enterprise LinuxOperating system
= 6.0= 7.0all versionsCVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify polkit package is installedRun `rpm -q polkit` (RHEL) or check for pkexec binary with `which pkexec` or `dpkg -l | grep polkit`Affected if polkit/pkexec is not installed on the system, the vulnerability does not apply
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Check installed polkit versionRun `rpm -q --qf '%{VERSION}-%{RELEASE}' polkit` (RHEL) or `dpkg -s polkit` (Debian) to retrieve the version numberAffected if The installed version matches Red Hat Enterprise Linux 6.0, 7.0, or any Freedesktop Polkit version - these are all affected until patched
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Verify pkexec supports --user optionRun `pkexec --help` and look for the --user option in the usage outputAffected if The --user option is listed and available, meaning unprivileged users can be specified as the target user for pkexec execution, which is the vulnerable code path
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Check for active polkit agentVerify if a polkit authentication agent is running with `ps aux | grep polkit` or check for polkit daemon with `systemctl status polkit`Affected if A polkit agent is active, allowing the --user nonpriv flow to be triggered by local users
If polkit/pkexec is installed with the --user option available (present in all affected versions), the environment is vulnerable to CVE-2016-2568 and users with local access could escape from pkexec to the parent terminal session.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpdate polkit to a version containing the fix for CVE-2016-2568. In the interim, avoid using pkexec with --user from untrusted contexts and ensure terminal sessions are not accessible to unprivileged users.
Fix this in Enterprise Linux
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-2568 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2016-2568 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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