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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 2 Jun 2023.
Linux KernelOperating system · Linux

CVE-2014-0196

MEDIUM · 5.5 CVSS v3.1 Published 2014-05-07
Fix available
A fix is available. Upgrade to 3.2.59 / 3.4.91 or later.
See remediation →
96/100
Remediation priority · Urgent
In the wild Public exploit Zero-click Patch available

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
The n_tty_write function in drivers/tty/n_tty.c in the Linux kernel through 3.14.3 does not properly manage tty driver access in the "LECHO & !OPOST" case, which allows local users to cause a denial of service (memory corruption and system crash) or gain privileges by triggering a race condition involving read and write operations with long strings.

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

Race condition vulnerability in Linux kernel's n_tty_write function (drivers/tty/n_tty.c) where improper tty driver access in the 'LECHO & !OPOST' configuration allows local users to trigger a race between read and write operations with long strings, leading to memory corruption and potential privilege escalation.

MitigationApply the upstream kernel patch (proper locking in n_tty.c) or upgrade to kernel version 3.14.4 or later. This is a kernel-level fix requiring recompilation and reboot.

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
Linux KernelOperating system
Affected:> 2.6.31, < 3.2.59>= 3.3, < 3.4.91>= 3.5, < 3.10.40>= 3.11, < 3.12.20>= 3.13, < 3.14.4= 2.6.31
Debian LinuxOperating system
Affected:= 6.0= 7.0
Enterprise LinuxOperating system
Affected:= 6.0
Enterprise Linux EusOperating system
Affected:= 6.3= 6.4
Enterprise Linux Server EusOperating system
Affected:= 6.3
LinuxOperating system
Affected:= 6
Ubuntu LinuxOperating system
Affected:= 10.04= 12.04= 12.10= 13.10= 14.04
Big Ip Access Policy ManagerApplication
Affected:>= 11.1.0, <= 11.5.1

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 the running kernel version
    Run `uname -r` or check `/proc/version` to obtain the exact kernel version string
    Affected if The kernel version falls within any of these vulnerable ranges: 2.6.31, > 2.6.31 to < 3.2.59, >= 3.3 to < 3.4.91, >= 3.5 to < 3.10.40, >= 3.11 to < 3.12.20, >= 3.13 to < 3.14.4
  2. Identify the distribution vendor and version
    Check `/etc/os-release` (or `lsb_release -a` on older systems) to determine the exact distribution and version
    Affected if The system runs Debian 6.0 or 7.0, Ubuntu 10.04, 12.04, 12.10, 13.10, or 14.04, RHEL 6.0, 6.3, or 6.4, Oracle Linux 6, or F5 Big-IP APM 11.1.0 to 11.5.1 (kernel version determines actual vulnerability)
  3. Verify if the n_tty driver is in use
    Check for active TTY sessions with `who` or `ps -t` and verify the kernel module is loaded via `lsmod | grep tty`
    Affected if Local users have active TTY sessions and the kernel version is within the affected ranges
  4. Check for the vulnerable tty configuration
    Examine if terminal sessions are using LECHO (local echo) without OPOST (output processing) by inspecting terminal settings via `stty -a` or reviewing application termios configurations
    Affected if A terminal session has LECHO enabled with OPOST disabled (the specific configuration that triggers the race condition)

The system is affected if it runs a Linux kernel version within the vulnerable ranges and has local users with TTY sessions using the LECHO without OPOST configuration.

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.

dbcve · scoped
Upgrade available Upgrade to 3.2.59 / 3.4.91 / 3.10.40 or later
Fixed in 3.2.593.4.913.10.40
Vendor patch bugzilla.redhat.com →
Interim mitigation

Apply the upstream kernel patch (proper locking in n_tty.c) or upgrade to kernel version 3.14.4 or later. This is a kernel-level fix requiring recompilation and reboot.

Recommended fix High confidence

Linux Kernel 3.2.59, 3.4.91, 3.10.40, or 3.12.20 (depending on kernel branch); or distribution-specific kernel update from vendor

  1. 1. Check current kernel version: uname -r
  2. 2. For Debian/Ubuntu: apt-get update && apt-get install linux-image-<version> (use a fixed version >= 3.2.59, 3.4.91, 3.10.40, or 3.12.20 depending on kernel branch)
  3. 3. For RHEL/CentOS: yum update kernel (install available kernel from vendor channels)
  4. 4. For Big-IP APM: Upgrade to version 11.5.2 or later from F5 Networks
  5. 5. Update bootloader configuration if necessary (e.g., /boot/grub/menu.lst)
  6. 6. Reboot system to load the patched kernel
Caveat Kernel upgrades may require reboot and can affect third-party kernel modules or drivers; test in staging first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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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-2014-0196 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
  • No spam, self-promotion, credentials, or personal data