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Util LinuxApplication · Kernel

CVE-2016-2779

HIGH · 7.8 CVSS v3.0 Published 2017-02-07
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
Zero-click

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 · unedited
runuser in util-linux 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 confidence

The runuser utility in util-linux contains a vulnerability where a local attacker can exploit the TIOCSTI ioctl to inject arbitrary characters into the terminal's input buffer, escaping the confined runuser session and potentially executing commands in the parent terminal session with elevated privileges.

MitigationApply the patched version of util-linux from distribution vendors. In high-risk environments, limit which local users can execute runuser/su and monitor for suspicious terminal activity.

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
Util LinuxApplication
Affected:= 2.24.2-1

CVSS 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
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check installed util-linux version
    Run 'rpm -q util-linux' on RHEL/CentOS/Fedora, 'dpkg -l util-linux' on Debian/Ubuntu, or 'runuser --version' to display version information
    Affected if The displayed version number is 2.24.2-1 or lower
  2. Verify runuser utility exists
    Confirm the runuser binary is present at /sbin/runuser or /usr/sbin/runuser using 'ls -la /sbin/runuser' or 'which runuser'
    Affected if The runuser command exists and is accessible to local users
  3. Check if TIOCSTI ioctl is available
    Review kernel configuration for CONFIG_TTY=y and verify TIOCSTI is not restricted in the system's security policy or seccomp configuration
    Affected if The TIOCSTI ioctl is permitted and unconfined users can access the terminal device associated with runuser sessions

A system is affected if the installed util-linux version is 2.24.2-1 or earlier AND the runuser utility is in use AND local users have access to the terminal input buffer through TIOCSTI.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the patched version of util-linux from distribution vendors. In high-risk environments, limit which local users can execute runuser/su and monitor for suspicious terminal activity.

Fix this in Util Linux Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,920
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-2779 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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